phywe-tess-che-lec-en

What you can learn about

CHEMISTRYL A B O R ATO RY E X P E R I M E N TS

LEC_1 05.06.2008 21:33 Uhr Seite 111

About Phywe

Founded in Göttingen, Germany in 1913 by Dr. Gotthelf Leimbach, Phywe Systeme GmbH & Co. KG quickly advanced

to one of the leading manufacturers of scientific equipment.

Over this period of more than 90 years Phywe has been putting quality and innovation into its products as a

fundamental requirement.

As a well known international supplier in the fields of science and engineering we have made a significant impact on

the market through high quality equipment.

Phywe products are made in Germany and in use throughout the world in the fields of education and research, from

primary schools right through to university level.

Up-to-date educational systems, planning and commissioning of scientific and engineering laboratories to meet

specific requirements are our daily business.

As a supplier of complete, fully developed and established systems, Phywe provides teaching and learning systems

for students as well as teacher demonstration experiments. The system ranges from simple, easy to operate

equipment intended for student use up to coverage of highly sophisticated and specialised university equipment

demands.

Phywe Systeme GmbH & Co. KG has achieved a very high standard based on research and technology and through

exchange of experiences with universities and high schools as well as with professors and teachers.

As experienced and competent manufacturer, we would gladly assist you in the

selection of the "right" experiments for your particular curricula.

LEC_1 05.06.2008 21:33 Uhr Seite 112


1

Contents

Page

LEC 01 Kinetic Theory

LEC 01.01 Velocity of molecules and the MAXWELL BOLTZMANNdistribution function 8

LEC 01.02 Gas viscosity: Estimation of molecular diameter 9LEC 01.03 Diffusion in gases: the diffusion coefficient

of bromine in air 10LEC 01.04 Determination of molar mass using the ideal gas law 11LEC 01.05 Determination of the molar mass of a liquid 12LEC 01.06 Determination of the molecular weight of a polymer

from intrinsic viscosity measurement 13LEC 01.07 Thermal conductivity of gases 14LEC 01.08 Viscosity measurements with the falling ball viscometer 15LEC 01.09 Viscosity of Newtonian and non-Newtonian liquids

(rotary viscometer) 16LEC 01.11 Gay-Lussac’s law 17LEC 01.12 Amontons’ law 18LEC 01.13 Boyle and Mariotte’s law 19

LEC 02 Thermochemistry / Calorimetry

LEC 02.01 Thermal equation of state and critical point 22LEC 02.02 Adiabatic coefficient of gases – Flammersfeld oscillator 23LEC 02.03 Heat capacity of gases 24LEC 02.04 Determination of the enthalpy of vaporization of liquids 25LEC 02.05 Partial molar volumes 26LEC 02.06 Determination of the mixing enthalpy

of binary fluid mixtures 27LEC 02.07 Determination of the hydration enthalpy of an electrolyte 28LEC 02.08 Determination of the enthalpy of neutralisation 29LEC 02.09 Determination of the melting enthalpy of a pure substance 30LEC 02.10 Boiling point elevation 31LEC 02.11 Freezing point depression 32LEC 02.14 Determination of the enthalpy of combustion with a

calorimetric bomb 33LEC 02.15 Determination of the heat of formation for water 34LEC 02.16 Determination of the heat of formation for CO2 and CO

(Hess law) 35LEC 02.17 Determination of the calorific value for heating oil

and the gross calorific value for olive oil 36LEC 02.18 Dilatometry 37

LEC 03 Chemical Equilibrium

LEC 03.01 Evaporative equilibrium 40LEC 03.02 Vapour pressure of mixtures of ideal fluids 41LEC 03.04 Boiling point diagram of a binary mixture 42LEC 03.05 Solubility diagram of two partially miscible liquids 43LEC 03.06 Miscibility gap in a ternary system 44LEC 03.07 Distribution equilibrium 45LEC 03.08 Solubility product 46LEC 03.09 Dissociation equilibrium 47LEC 03.10 Complex formation equilibrium 48LEC 03.11 Dissociation constants 49LEC 03.13 The melting point of a binary system 50LEC 03.14 Law of integral ratio of volumes 51LEC 03.15 Determination of the number of theoretical trays

in a distillation column 52LEC 03.16 Fractional distillation with the bubble tray column 53LEC 03.17 Chromatographic separation procedures:

gas chromatography 54

ContentsPage

LEC 04 Interfacial Chemistry

LEC 04.01 Determination of the surface tension of pure liquids with the bubble pressure method 56

LEC 04.02 Determining surface tension using the ring method (Du Nouy method) 57

LEC 04.03 Free films 58LEC 04.04 Contact angle 59LEC 04.06 Electrokinetic potential 60LEC 04.07 Electrophoretic mobility 61LEC 04.08 Adsorption isotherms 62

LEC 05 Chemical Kinetics

LEC 05.01 Saponification rate of tert-butyl chloride 64LEC 05.02 Reaction rate and activation energy of the acid hydrolysis

of ethyl acetate 65LEC 05.03 Kinetics of saccharose inversion 66LEC 05.07 Halogen exchange rate 67LEC 05.08 Conductometric measurements on the saponification

of esters 68LEC 05.09 Enzyme kinetics: Determination of the Michaelis constant 69LEC 05.10 Enzyme kinetics: Inhibition and poisoning of enzymes 70

LEC 06 Electro Chemistry

LEC 06.01 Charge transport in solids 72LEC 06.02 Charge transport in liquids 73LEC 06.03 Ion migration velocity 74LEC 06.04 Transference numbers 75LEC 06.05 The temperature dependence of conductivity 76LEC 06.06 Conductivity of strong and weak electrolytes 77LEC 06.07 Conductiometric titration 78LEC 06.08 Determination of the conductivity coefficient 79LEC 06.09 The Nernst equation 80LEC 06.10 Determination of the solubility products

of the silver halides 81LEC 06.11 Determination of diffusion potentials 82LEC 06.12 Temperature dependence of the electromotive force 83LEC 06.13 Potentiometric titration 84LEC 06.14 Precipitation titration 85LEC 06.15 pH measurement 86LEC 06.16 Titration curves and buffering capacity 87LEC 06.17 Potentiometric pH titration

(phosphoric acid in a soft drink) 88LEC 06.18 Electrode kinetics: The hydrogen overpotential of metals 89LEC 06.20 Amperometric equivalent point determination

with the dead stop method 90LEC 06.21 Determination of Faraday’s constant 91LEC 06.22 Electrogravimetric determination of copper 92

LEC 07 Photometry and Photochemistry

LEC 07.01 Absorption of light 94LEC 07.03 Excitation of molecules 95LEC 07.04 Absorption spectra and pKa values of p-methoxyphenol 96

LEC_1 05.06.2008 21:33 Uhr Seite 1

Phywe in the University City of Göttingen –

2

Natural sciences have a longstanding

tradition in Göttingen. More than 40 Nobel

prizewinners coming from all sorts of

scientific disciplines and numerous university

institutes successfully conduct research in

practically all areas of science.

The following research institutions and

university institutes are located in Göttingen:

Academy of Science, several Max-Planck

institutes, the German Primate Centre, the

Centre of Molecular Physiology of the Brain,

the Centre of Molecular Life Science –

to name just a few.

We are in contact with these institutions and

exchange our views with them to ensure that

the latest trends and scientific innovations

are always reflected in the product range of

Phywe Systeme GmbH & Co. KG.

LEC_1 05.06.2008 21:33 Uhr Seite 2

A Center of Natural Sciences in Germany

3

GÖTTINGEN is a city of teaching and research. Scientific equipment, teaching

equipment and laboratory installations developed and produced in this city are famous

throughout the world.

Göttingen would not be what it is without its university.

“Georgia Augusta” was founded in 1734 and by 1777 it was Germany‘s largest

university, with 700 students. It still is one of the leading universities in Germany, with

14 faculties, significant scientific facilities and more than 30,000 students.

The gracious Goose Girl (“Gänseliesel”) on the market place well is the most kissed girl

in Germany. Why? Because every newly graduated doctor must kiss the cold beauty on

her bronze mouth. That is Göttingen tradition.

Doctor’s kiss for the Goose Girl

LEC_1 05.06.2008 21:33 Uhr Seite 3

4 PHYWE Systeme GmbH & Co. KG · D-37070 GöttingenLaboratory Experiments Chemistry

Laboratory Experiments Chemistry LEC

Picture andEquipment List guarantee time-savingand easy conducting of the experiment.

Theory and evaluation states full theoryinvolved and shows graphical and numericalexperimental results including error calcules.

Example for measurementparameters for easy andsafe experimentation.

All experiments are uniformly built-upand contain references such asRelated topics and Principle and taskto introduce the subject.

LABORATORY EXPERIMENTS

CHEMISTRY

1650

4.12

Laboratory Experiments

W. Schäfer, J. Klunker

T. Schelenz, T. Meier

A. Symonds, S. Iwanek

W. Kutzborski

Experimental literature

Laboratory Experiments Chemistry

Long Version No. 16504.12

The experiments in the PHYWE Publication Series “Laboratory Experiments Chemistry” are intended for the

heads of chemistry laboratory courses at universities, colleges and similar institutions and also for advanced

courses in high schools.

LEC_1 05.06.2008 21:33 Uhr Seite 4

5PHYWE Systeme GmbH & Co. KG · D-37070 Göttingen Laboratory Experiments Chemistry

LEC Laboratory Experiments Chemistry

Quantity

Order No.

Please specify thisOrder No. if you would liketo order the completeexperiment.

The present volume which has been developed by PHYWE, complements the previously existing collection of

about 80 experiments in seven chapters as the comprehensive Table of Contents shows. In this brochure we

present the experiments in short form. The experiments can be ordered or offered completely or partially, if

desired, in accordance with the Comprehensive Equipment Lists. On request, we will gladly send you detailed

experimental descriptions.

You can order the experiments as follows:

� Didactically adap-ted descriptions ofexperiments – easy,direct preparationby the students ispossible

� Comprehensive experiments – cover the entire range of classicaland modern chemistry

� Developed and proven bypracticians – unproblematical andreliable performance

� Complete equipment offeringmodular experimental set-up –multiple use of individual devices,cost effective and flexible

� Excellent measurement accuracy – results agree with theory

� Computer-assisted experiments –simple, rapid assessement of theresults

Cobra3 Chem-Unit 12153.00 1Power supply, 12 V 12151.99 1Data cable, RS 232 14602.00 1Software Cobra3 Chem-Unit 14520.61 1Connecting cord, l = 250 mm, red 07360.01 1Connecting cord l = 250 mm, blue 07360.04 1Control unit for gas chromatography 36670.99 1Measuring probe for gas chromatography 36670.10 1Glass jacket 02615.00 1Gas separation column 36670.00 1Rubber caps 02615.03 1Soap bubble flow meter 36675.00 1H-base -PASS- 02009.55 1Support rod, l = 750 mm 37692.00 2Right angle clamp 37697.00 6......Acetone, 250 ml 30004.25 1Ethyl alcohol, absolute, 500 ml 30008.50 1Ethyl acetate, 250 ml 30075.25 1Butane burner Labogaz 206 32178.00 1Butane cartridge C 206 47535.00 1Water, distilled, 5 l 31246.81 1Soap solution • Drying oven • PC, Windows® 95 or higher

What you need:

Chromatographic separation procedures:gas chromatography P3031711

LEC_1 05.06.2008 21:33 Uhr Seite 5


The experiments in the Phywe publication series “Laboratory Experiments”

are intended for the heads of laboratories,

colleges of advanced technology, technical

colleges and similar institutions and also

for advanced courses in high schools.

Laboratory Experiments Physics is

also available on CD-ROM.

Available in English.

For the student system “Advanced Optics

and Laser Physics” a special brochure

is available in English.

Special brochures

Additionally there are special

brochures for our particularly suc-

cessful teaching systems TESS (avail-

able in German, English, French and

Spanish), Cobra3 (available in German,

English) and Natural Sciences on the

board (available in German, English).

PHYSICS · CHEMISTRY · BIOLOGY

6

PHYSICS – CHEMISTRY – BIOLOGY

The comprehensive catalogue for physics,

chemistry and biology. Additionally you can

find a large number of laboratory materials

and an insight in our particularly successful

teaching systems TESS, Cobra3 and

Natural Sciences on the board.

Available in German, English and Spanish.

– catalogues, brochures

and more…

LEC_1 05.06.2008 21:33 Uhr Seite 6


Kinetic TheoryContents

LEC 01.01 Velocity of molecules and the MAXWELL BOLTZMANNdistribution function

LEC 01.02 Gas viscosity: Estimation of molecular diameter

LEC 01.03 Diffusion in gases: the diffusion coefficient of bromine in air

LEC 01.04 Determination of molar mass using the ideal gas law

LEC 01.05 Determination of the molar mass of a liquid

LEC 01.06 Determination of the molecular weight of a polymer fromintrinsic viscosity measurement

LEC 01.07 Thermal conductivity of gases

LEC 01.08 Viscosity measurements with the falling ball viscometer

LEC 01.09 Viscosity of Newtonian and non-Newtonian liquids (rotary viscometer)

LEC 01.11 Gay-Lussac’s law

LEC 01.12 Amontons’ law

LEC 01.13 Boyle and Mariotte’s law1

LEC_1 05.06.2008 21:33 Uhr Seite 7


Kinetic Theory LEC 01

Principle and tasksBy means of the model apparatus forkinetic theory of gases, the motion ofgas molecules is simulated and thevelocity is determined by registrationof the throw distance of the glassballs. This velocity distribution iscompared to the theoretical MAX-WELL-BOLTZMANN equation.

Distribution of molecule velocities of oxygen at 273 K.


� Kinetic theory of gases� Temperature � Model kinetic energy� Average velocity� Velocity distribution

Kinetic gas theory apparatus 09060.00 1

Receiver with recording chamber 09061.00 1

Power supply, variable, 15 VAC/ 12 VDC/ 5 A 13530.93 1

Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1

Digital stroboscope 21809.93 1

Stopwatch, digital, 1/100 sec. 03071.01 1

Tripod base -PASS- 02002.55 2

Connecting cord, l = 750 mm, red 07362.01 1

Connecting cord, l = 750 mm, blue 07362.04 1

Test, tube, d = 16 mm, l = 16 cm 37656.10 1

Test tube rack for 12 tubes, wood 37686.00 1

Glass beaker, 50 ml, tall 36001.00 5

Spoon 40874.00 1

What you need:

Velocity of molecules and the MAXWELL BOLTZMANNdistribution function P3010101

01.01 Velocity of molecules and the MAXWELL BOLTZMANN distribution function

Experimental and theoretical velocity distribution in the model experiment.

theoretical distributionexperimental distribution

LEC_1 05.06.2008 21:33 Uhr Seite 8


Gas viscosity: Estimation of molecular diameter 01.02

Principle and tasksThe viscosity of a gas relates to itsresistance to flow. It is determinedby the rate of transfer of the flowmomentum from the faster movinglayers to the slower ones.

The so-called transpiration methodsprovide a convenient way of measur-ing gas viscosities. In the approachused here, the rate of flow of the gasis recorded by monitoring the evacu-ation of a vessel through a capillarytube under a constant pressure dif-ferential. Using simple gas kinetictheory, the molecular diameter forthe gas can be estimated.


H-base -PASS- 02009.55 2

Support rod, l = 750 mm 02033.00 1

Universal clamp 37715.00 4

Right angle clamp 37697.00 3

Gas syringe holder with stop 02058.00 1

Gas syringe, 100 ml, with 3-way cock 02617.00 1

Capillary tube, glass, di = 0.15 mm, l = 100 mm 40582.00 1

Security bottle with manometer 34170.88 1

Water jet pump 02728.00 1

Rubber tubing, vacuum, di = 6 mm 39286.00 3

Hose clips, d = 12…20 mm 40995.00 2

Stop watch, digital, 1/100 s 03071.01 1

Weather monitor, LCD 87997.10 1

Vernier calliper 03010.00 1

Fine control valve 33499.00 1

Silicone grease, 100 g, 1 tube 31863.10 1

Compressed gas, nitrogen, 12 l 41772.04 1

Compressed gas, carbon dioxide, 21 g 41772.06 1

Compressed gas, hydrogen, 12 l 41772.01 1

Compressed gas, helium, 12 l 41772.03 1

What you need:

Gas viscosity: Estimation of molecular diameterP3010201


� Kinetic theory of gases� Mean free path� Transport properties� Laminar and turbulent flow� Poiseuille’s formula

LEC_1 05.06.2008 21:33 Uhr Seite 9


01.03. Diffusion in gases: the diffusion coefficient of bromine in air

Principle and tasksDiffusion arises from the flow ofmatter down a concentration gradi-ent. In the evaporation method, astationary concentration gradient isachieved in which the concentrationfalls linearly with distance. Underthese conditions the diffusion co-effiecient of the diffusing substancemay be calculated by a direct appli-cation of Fick’s first law of diffusion.

H-base -PASS- 02009.55 2

Support rod, l = 750 mm 02033.00 1



Tube connector, T-shaped, IGJ 29 35859.00 1

Erlenmeyer flask, 250 ml, IGJ 29/32 46126.00 1

Gas-washing bottle with glass frit, 100 ml, IGJ 29/32 36691.01 1

Gas-washing bottle, 100 ml, IGJ 29/32 36691.00 2

Teflon collars, NS 29 43617.00 1


Pinchcock, w = 15 mm 43631.15 1



Hose clips, d = 12…20 mm 40995.00 2


Thermometer, -10…+100°C 38056.00 1


Vernier calliper 03010.00 1

Beaker, 400 ml, short 36014.00 1

Glass rods, d = 5 mm, l = 200 mm 40485.03 1

Pasteur pipettes 36590.00 1

Rubber bulbs 39275.03 1

Wash bottle, 500 ml 33931.00 1

Spoon 33398.00 1

Bromine, 50 ml 30046.10 1

Iron(II) sulphate, 500 mg 30072.50 1

Sulphuric acid 95…98%, 500 ml 30219.50 1

Water, distilled, 5 l 31246.81 1

What you need:

Diffusion in gases: the diffusion coefficientof bromine in air P3010301



� Kinetic theory of gases� Transport properties� Fick’s laws of diffusion� Self and mutual diffusion

coefficients

LEC_1 05.06.2008 21:33 Uhr Seite 10


Determination of molar mass using the ideal gas law 01.04


Principle and tasksAll gases may be considered, to afirst approximation, to obey the idealgas equation which relates the pres-sure p, volume V, temperature T andamount of substance n of a gas. Ifthe volume occupied by a knownmass of gas is measured at a giventemperature and pressure, the equa-tion can be used to estimate themolar mass of a gas.

In this experiment the molar massesof gases helium, nitrogen, carbondioxide and methane are determined.

� Molar mass� Properties of gases� Ideal (perfect) and real gases� Equations of state of ideal

gases

H-base -PASS- 02009.55 2

Support rod, stainless steel, l = 750 mm 02033.00 1



Gas syringe holder with stop 02058.00 1

Gas syringe, 100 ml, with 3-way cock 02617.00 1

Glass sphere with 2 stopcocks, 100 ml 36810.00 1

Safety bottle with manometer 34170.88 1

Vacuum pump, one-stage 02750.93 1

Oil mist filter 02752.00 1

Adapter for vacuum pump 02657.00 1




Hose clip, d = 8…12 mm 40996.00 4

Hose clip, d = 12…20 mm 40995.00 2

Weather Monitor, LCD 87997.10 1



Compressed gas, nitrogen, 12 l 41772.04 1


Compressed gas, methane, 12 l 41772.08 1

Compressed gas, helium, 12 l 41772.03 1

What you need:

Determination of molar mass usingthe ideal gas law P3010401


LEC_1 05.06.2008 21:33 Uhr Seite 11


01.05. Determination of the molar mass of a liquid

Principle and tasksThe molar mass of a liquid is deter-mined by evaporation of the liquid atconstant temperature and pressureand measuring the volume of theformed vapour by means of a cali-brated gas syringe. In this experi-ment the molar masses of diethylether and methanol are determined.

H-base -PASS- 02009.55 1

Support rod, l = 250 mm 02031.00 2



Glass jacket 02615.00 1

Gas syringe, 100 ml 02614.00 1

Laboratory thermometer, -10…+150°C 38058.00 2


Rubber caps 02615.03 1

Syringe, 1 ml 02593.03 1

Cannula 0.6�60 mm 02593.04 1


Beads, 200 g 36937.20 1

Rubber tubing, di = 6 mm 39282.00 1

Funnel, glass, do = 80 mm 34459.00 1


Heating apparatus 32246.93 1

Power regulator 32288.93 1

Methanol, 500 ml 30142.50 1

Diethyl ether, 250 ml 30007.25 1


Paper towels

What you need:

Determination of the molar mass of a liquidP3010501



� Ideal (perfect) and real gases � Equations of state of ideal

gases� Gas volumetry� Vapour-density method

(Victor Meyer)

LEC_1 05.06.2008 21:33 Uhr Seite 12


Determination of the molecular weight of a polymer from intrinsic viscosity measurement 01.06


Principle and tasksThe viscosity of a liquid is effectivelydetermined by the strength of the in-termolecular attractive forces. In so-lutions, the viscosity of the solventcan alter significantly depending onthe type and concentration of solutepresent. Due to their size, macro-molecules have a very considerableimpact on the viscosity of the solvent.Viscosity measurements can be usedto estimate the mean molecular massof a macromolecule if something isknown about its conformation.

Using a thermostatic capillary vis-cometer, the viscosities of solutionsof polystyrene in toluene are meas-ured over a range of five polymerconcentrations and the molecularweight is estimated.

Plot used to determine the intrinsic viscosity �. Data for polystyrene intoluene at 25.0°C.

� Viscosity of liquids � Ostwald capillary viscometer� Poiseuilles’s equation� Macromolecules

Immersion thermostat, 100°C 08492.93 1

Bath for thermostat, 6 l, Makrolon 08487.02 1

Accessory set for immersion thermostat 08492.01 1

Retort stand, h = 750 mm 37694.00 1



Capillary viscometer, 0.4 mm 03102.03 1


Analytical balance CPA 224S (220 g/0.1 mg), set with software 49221.88 1

Weighing dishes, 80�50�14 mm 45019.05 1

Volumetric flask, 250 ml 36550.00 1


Volumetric pipette, 5 ml 36577.00 6




Pipettor 36592.00 1

Pipette dish 36589.00 1





Hose clips, d = 8…12 mm 40996.01 4

Beaker, 250 ml, tall 36004.00 4

Graduated cylinder, 100 ml 36629.00 1

Glass rods, d = 5 mm, l = 200 mm 40485.03 1

Spoon 33398.00 1




What you need:


Polystyrene, granulated, 100 g 48492.25 1

Toluene, 250 ml 30236.25 3

Acetone, chem. pure, 250 ml 30004.25 1

Hydrochloric acid, 37%, 1000 ml 30214.70 1

Nitric acid, 65%, 1000 ml 30213.70 1

Water, distilled, 5 l 31246.81 1Determination of the molecular weight of a polymerfrom intrinsic viscosity measurement P3010601

LEC_1 05.06.2008 21:33 Uhr Seite 13


01.07 Thermal conductivity of gases

Principle and tasksThe thermal conductivity of a gas isexpressed by the coefficient of ther-mal conductivity which is a functionof the average particle velocity andthe free path distance. In the exper-imental set-up there is a functionalcorrelation between the thermalconductivities of the gases at themeasuring probe and the voltagesignal at the control unit. If the loga-rithm of the respective coefficient ofthermal conductivity is plottedagainst the measured voltages, astraight line is obtained which canbe used as a calibration curve for thedetermination of the coefficients ofadditional gases.

Calibration curve for the determination of coefficients of thermal conductivity.

Measuring probe for gas chromatograph 36670.10 1

Control unit for gas chromatograph 36670.99 1

Digital multimeter 07134.00 1

Connection cord, l = 250 mm, blue 07360.04 1

Connection cord, l = 250 mm, red 07360.01 1








Steel cylinder helium, 2 l, filled 41776.00 1

Reducing valve for helium 33481.00 1

Table stand for 2 l steel cylinders 41774.00 1

Wrench for steel cylinders 40322.00 1


Compressed gas, methane, 12 l 41772.08 1


Silicone fluid for heating bath 31849.50 1

What you need:

Thermal conductivity of gasesP3010701



� Thermal conductivity� Coefficient of thermal

conductivity� Gas chromatography

LEC_1 05.06.2008 21:33 Uhr Seite 14


Viscosity measurements with the falling ball viscometer 01.08


Principle and tasksDue to internal friction among theirparticles, liquids and gases have dif-ferent viscosities. The viscosity is afunction of the substance’s structureand its temperature.

In a first experiment the viscositiesof methanol-water mixtures of vari-ous composition are measured atconstant temperature. Subsequentlythe viscosities of water and metha-nol are determined at different tem-peratures.

Dependence of the viscosity � of the methanol/water system on the compo-sition described by the mass fraction w at constant temperature (T = 298 K).

� Newtonian liquid� Stokes law� Fluidity� Dynamic and kinematic

viscosity� Viscosity measurements

Falling ball viscometer 18220.00 1

Thermometer, +24… +51°C 18220.02 1






Universal clamp with joint 37716.00 1

Pycnometer, calibrated, 25 ml 03023.00 1



Glass beaker, 250 ml, short 36013.00 1



Hose clips, d = 8…12 mm 40996.01 6


Stopwatch, digital, 1/100 s 03071.01 1



Methanol, 500 ml 30142.50 2


What you need:

Viscosity measurements with the falling ballviscometer P3010801

Temperature dependence of the dynamic viscosity � of water (o) andmethanol (+) respectively.


LEC_1 05.06.2008 21:33 Uhr Seite 15


01.09. Viscosity of Newtonian and non-Newtonian liquids (rotary viscometer)

Principle and tasksThe viscosity of liquids can be deter-mined with a rotation viscometer. Itconsists of a motor with variablerotation speed driving a cylinder im-mersed in the liquid to be investigat-ed with a spiral spring. The viscosityof the liquid generates a moment ofrotation at the cylinder which can bemeasured with the aid of the torsionof the spiral spring and read on ascale.

Moment of rotation as a function of the frequency for a Newtonian liquid(+ Glycerine, o Liquid paraffin).

Rotary viscometer 18221.93 1

Support base -PASS- 02005.55 1

Support rod, l = 500 mm 02032.00 1


Magnetic heating stirrer 35720.93 1

Electronic temperature control 35721.00 1

Magnetic stirrer bar, l = 30mm 46299.02 1

Separator for magnetic bars 35680.03 1



Glass rod, l = 200 mm, d = 5 mm 40485.03 2

Glycerol, 250 ml 30084.25 2

Liquid paraffin, 250 ml 30180.25 1

Castor oil, 250 ml 31799.27 2


What you need:

Viscosity of Newtonian and non-Newtonian liquids(rotary viscometer) P3010901



� Shear stress� Internal friction� Viscosity� Newtonian liquid� non-Newtonian liquid

Moment of rotation as a function of frequency for a non-Newtonian liquid(chocolate at 302 K).

LEC_1 05.06.2008 21:33 Uhr Seite 16


Gay-Lussac’s law 01.11


Principle and tasksThe state of a gas is determined bytemperature, pressure and amount ofsubstance. For the limiting case ofideal gases, these state variables arelinked via the general equation ofstate. For a change of state underisobaric conditions this equationbecomes the 1st law of Gay-Lussac.The validity of Gay-Lussac’s law isexperimentally investigated for aconstant amount of gas (air).

Dependence of the volume on the temperature under isobaric conditions.

� Coefficient of thermalexpansion

� General equation of state forideal gases

� Universal gas constant� Gay-Lussac’s law

Cobra3 Basic-Unit, USB 12150.50 * 1

Power supply 12V/2A 12151.99 1

Temperature measuring module NiCr-Ni 12104.00 * 1

Thermocouple, NiCr-Ni, sheated 13615.01 1

Software Cobra3 Gas laws 14516.61 * 1


Glass syringe, 100 ml 02614.00 1



H-base -PASS- 02009.55 1

Support rod, l = 250 mm 02031.00 2



Magnet, l = 200 mm, d = 10 mm 06311.00 1

Magnetic stirring bar, l = 30 mm 46299.02 1




Silicone tubing, di = 7 mm 39296.00 1

PC, Windows® 95 or higher

What you need:

Gay-Lussac’s lawP3011111


Changes in the equipment required for use of the Chem-Unit:(instead of * above mentioned)

Cobra3 Chem-Unit 12153.00 1

Software Cobra3 Chem-Unit 14520.61 1

Gay-Lussac’s lawP3011140

LEC_1 05.06.2008 21:33 Uhr Seite 17


01.12 Amontons’ law

Principle and tasksThe state of a gas is determined bytemperature, pressure and amount ofsubstance. For the limiting case ofideal gases, these state variables arelinked via the general equation ofstate. For a change of state underisochoric conditions this equationbecomes Amontons’ law.

In this experiment it is investigatedwhether Amontons’ law is valid for aconstant amount of gas (air).

Dependence of the pressure on the temperature under isochoric conditions.

Cobra3 Basic-Unit, USB 12150.50 1


Data cable, RS232 14602.00 1

Measuring module, pressure 12103.00 1

Module converter 12150.04 1

Cobra3 sensor, -10…120°C 12120.00 1

Software Cobra3 Gas laws 14516.61 1





H-base -PASS- 02009.55 1

Support rod, l = 250 mm 02031.00 2




Magnet, l = 200 mm, d = 10 mm 06311.00 1

Magnetic stirring bar, l = 30 mm 46299.02 1



Tubing adaptor 3-5 / 6-10 mm 47517.01 1



Hose clips, d = 8…12 mm 40996,01 2

Motor oil


What you need:

Amontons’ lawP3011211



� Thermal tension coefficient� General equation of state

for ideal gases� Universal gas constant� Amontons’ law

LEC_1 05.06.2008 21:33 Uhr Seite 18


Boyle and Mariotte’s law 01.13


Principle and tasksThe state of a gas is determined bytemperature, pressure and amount ofsubstance. For the limiting case ofideal gases, these state variables arelinked via the general equation ofstate. In case of isothermal processcontrol this equation becomes Boyleand Mariotte’s law.

The validity of Boyle and Mariotte’slaw is experimentally investigatedfor a constant amount of gas (air).From the resulting relationship theuniversal gas constant is calculated.

Correlation between volume and pressure under isothermic conditions.

� Cubic compressibilitycoefficient

� General equation of state for ideal gases

� Universal gas constant� Boyle and Mariotte’s law



Data cable, RS232 14602.00 1

Measuring module, pressure 12103.00 1


Cobra3 sensor, -10…120°C 12120.00 1

Software Cobra3 Gas laws 14516.61 1



H-base -PASS- 02009.55 1

Support rod, l = 250 mm 02031.00 2






Tubing adaptor 3-5 / 6-10 mm 47517.01 1



Hose clips, d = 8…12 mm 40996.01 2

Motor oil


What you need:

Boyle and Mariotte’s lawP3011311


LEC_1 05.06.2008 21:33 Uhr Seite 19

20

LEC_1 05.06.2008 21:33 Uhr Seite 20

2 Contents

LEC 02.01 Thermal equation of state and critical pointLEC 02.02 Adiabatic coefficient of gases – Flammersfeld oscillatorLEC 02.03 Heat capacity of gasesLEC 02.04 Determination of the enthalpy of vaporization of liquidsLEC 02.05 Partial molar volumesLEC 02.06 Determination of the mixing enthalpy of binary fluid mixturesLEC 02.07 Determination of the hydration enthalpy of an electrolyteLEC 02.08 Determination of the enthalpy of neutralisationLEC 02.09 Determination of the melting enthalpy of a pure substanceLEC 02.10 Boiling point elevationLEC 02.11 Freezing point depressionLEC 02.14 Determination of the enthalpy of combustion with a

calorimetric bombLEC 02.15 Determination of the heat of formation for waterLEC 02.16 Determination of the heat of formation for CO2 and CO (Hess law)LEC 02.17 Determination of the calorific value for heating oil and the

gross calorific value for olive oilLEC 02.18 Dilatometry

Thermochemistry/Calorimetry

LEC_1 05.06.2008 21:34 Uhr Seite 21


02.01 Thermal equation of state and critical point

Principle and tasksA substance which is gaseous undernormal conditions is enclosed in avariable volume and the dependenceof pressure on volume is recorded atdifferent temperatures. The criticalpoint is determined graphically froma plot of the isotherms.

Interaction potential dependend on the molecular distance.

Critical point apparatus 04364.10 1




Gasket for GL 18, 8 mm hole 41240.03 1

Laboratory thermometer, -10…+100°C 38056.00 1

Vacuum pump, one stage 02750.93 1

Adapter for vacuum pump 02657.00 1



Support rod, l = 500 mm 02032.00 1






Pinchcock, w = 15 mm 43631.15 1

Hose clip, d = 8…12 mm 40996.01 4

Hose clip, d = 12…20 mm 40995.00 2

Mercury tray 02085.00 1

Compressed gas, ethane, 14 g 41772.09 1

What you need:

Thermal equation of state and critical pointP3020101

Thermochemistry / Calorimetry LEC 02


� Equation of state� Van der WAALS equation� Boyle temperature� Critical point� Interaction potential� Molecule radius

E/�

�m

repulsion

attraction

�

LEC_1 05.06.2008 21:34 Uhr Seite 22


Adiabatic coefficient of gases – Flammersfeld oscillator 02.02


Principle and tasksA mass oscillates on a volume of gasin a precision glass tube. The oscilla-tion is maintained by leading escap-ing gas back into the system. Theadiabatic coefficient of various gasesis determined from the periodic timeof the oscillation.

� Equation of adiabatic changeof state

� Polytropic equation� Rüchardt’s experiment � Thermal capacity of gases

Gas oscillator, Flammersfeld 04368.00 1


Aspirator bottle, 1000 ml 34175.00 1

Air control valve 37003.00 1

Light barrier with counter 11207.30 1

Power supply 5 VDC / 2.4 A 11076.99 1

Micrometer 03012.00 1

Glass tubes, right-angled 36701.52 1

Rubber stopper, d = 17 / 22 mm, 1 hole 39255.01 1

Rubber stopper, d = 26 / 32 mm, 1 hole 39258.01 1


Sliding weight balance, 101 g 44012.01 1

Aquarium pump, 230 VAC 64565.93 1

Aneroid barometer 03097.00 1



Support rod -PASS-, square, l = 400 mm 02026.55 1

Right angle clamp -PASS- 02040.55 2


Reducing valve for carbon dioxide / helium 33481.00 1

Reducing valve for nitrogen 33483.00 1

Steel cylinder, carbon dioxide, 10 l, filled 41761.00 1

Steel cylinder, nitrogen,10 l, filled 41763.00 1

What you need:

Adiabatic coefficient of gases –Flammersfeld oscillator P3020201


LEC_1 05.06.2008 21:34 Uhr Seite 23


02.03 Heat capacity of gases

Principle and tasksHeat is added to a gas in a glass ves-sel by an electric heater which isswitched on briefly. The temperatureincrease results in a pressure in-crease which is measured with amanometer. Under isobaric condi-tions a temperature increase resultsin a volume dilatation that can beread from a gas syringe. The molarheat capacities Cv and Cp are calcu-lated from pressure and volumechange.

Pressure change �p as a function of the heat-up time �t. U = 4.59 V, I = 0.43 A.

Precision manometer 03091.00 1

Barometer / Manometer, hand-held 07136.00 1

Digital counter, 4 decades 13600.93 * 1

Digital multimeter 07134.00 * 2

Mariotte flask, 10 l 02629.00 1


Stopcock, 1-way, straight 36705.00 1

Stopcock, 3-way, T-shaped, capillary 36732.00 1

Rubber stopper, d = 26 / 32 mm, 3 holes 39258.14 1

Rubber stopper, d = 50.5 / 59.5 mm, 1 hole 39268.01 1


Nickel electrode, d = 3 mm, with socket 45231.00 2

Nickel electrode 76�40 mm 45218.00 1

Chrome-nickel wire, d = 0.1 mm, l = 100 m 06109.00 1

Scissors, straight, blunt, l = 140 mm 64625.00 1


Connecting cord, l = 500 mm, yellow 07361.02 * 2




Two-way switch, single pole 06030.00 1





What you need:

Heat capacity of gasesP3020301



� 1st law of thermodynamics� Universal gas constant � Isobars� Isotherms� Isochors and adiabatic

changes of state

Changes in the equipment required for use of the Basic-Unit:(instead of * above mentioned)


Power supply 12 V/ 2 A 12151.99 1

Cobra3 Universal writer software 14504.61 1


Heat capacity of gaseswith Cobra3 Basic-Unit P3020311

LEC_1 05.06.2008 21:34 Uhr Seite 24


Determination of the enthalpy of vaporization of liquids 02.04


Principle and tasksThe vaporization of a liquid occurswith heat absorption. To determinethe enthalpy of vaporization, aknown mass of the liquid which is tobe investigated is vaporized in a spe-cial vaporization vessel in a currentof air. The quantity of heat absorbedwhich corresponds to the enthalpy ofvaporization can be calorimetricallydetermined.

Temperature-time curve of the vaporisation of diethyl ether and determiningthe heat capacity of the system.

� Enthalpy of vaporisation� Entropy of vaporisation� Trouton’s rule� Calorimetry� Heat capacity



Temperature measuring module Pt100 12102.00 1

Software Cobra3 Temperature 14503.61 1

Temperature probe Pt100 11759.01 1

Calorimeter, transparent 04402.00 1

Evaporation vessel for calorimeter 04405.00 1

Heating coil with sockets 04450.00 1

Work and power meter 13715.93 1

Universal power supply 13500.93 1

Connection cable, l = 500 mm, black 07361.05 4


Magnetic stirrer bar, l = 30 mm, oval 35680.04 1


Support rod, l = 500 mm, M10 thread 02022.20 1





Precision balance CPA 6202S (6200 g/0.01 g),set with software 49226.88 1




Erlenmeyer flask, 250 ml, wide 36134.00 1




Hose clip, d = 12…20 mm 40995.00 5

Air control valve 37003.00 1

What you need:


Syringe, 20 ml 02591.03 1

Cannula, 0.9�70 mm 02597.04 1


Diethyl ether, 250 ml 30007.25 1

Methanol, 500 ml 30142.50 1



Determination of the enthalpy of vaporizationof liquids P3020411

LEC_1 05.06.2008 21:34 Uhr Seite 25


02.05 Partial molar volumes

Principle and tasksDue to intermolecular interactions,the measured total volume resultingfrom the mixture of two real liquidsdeviates from the calculated volumeof the individual components. To de-scribe this non-ideal behaviour inthe mixing phase, one defines partialmolar quantities which are depen-dent on the system composition.These values can be experimentallydetermined, in this case by mea-suring the densities of differentethanol-water mixtures with pycno-meters.

Dependence of the mean molar mixing volumes �MV on the composition ofdifferent ethanol /water mixtures.





H-base -PASS- 02009.55 1

Support rod, l = 250 mm 02031.00 1

Support rod, l = 500 mm 02032.00 2



Pycnometer, calibrated, 25 ml 03023.00 9

Bottle, narrow neck, 100 ml 41101.01 9






Hose clip, d = 8…12 mm 40996.01 4


Ethyl alcohol, absolute, 500 ml 30008.50 1

Water, distilled 5 l 31246.81 1

What you need:

Partial molar volumesP3020501



� Principles of thermodynamics� Ideal and non-ideal behaviour

of gases and liquids� Volume contraction� Molar and partial molar

quantities

LEC_1 05.06.2008 21:34 Uhr Seite 26


Determination of the mixing enthalpy of binary fluid mixtures 02.06


Principle and tasksWhen two miscible liquids are mixed,a positive or negative heat effectoccurs, which is caused by the inter-actions between the molecules. Thisheat effect is dependent on themixing ratio. The integral mixingenthalpy and the differential molarmixing enthalpy can be determinedby calorimetric measurements of theheat of reaction.

Temperature-time curve of the mixing of two miscible fluids and determiningthe heat capacity of the system.

� Molar mixing enthalpy� Real and ideal behaviour� Fundamental principles of

thermodynamics� Calorimetry� Heat capacity















Hose clips, d = 8…12 mm 40996.01 4










Erlenmeyer flask, 250 ml, narrow neck, PN 29 36424.00 2

Erlenmeyer flask, 100 ml, narrow neck, PN 19 36418.00 5


Powder funnel, do = 65 mm 34472.00 1



What you need:




Water, distilled, 5l 31246.81 1


Determination of the mixing enthalpyof binary fluid mixtures P3020611

LEC_1 05.06.2008 21:34 Uhr Seite 27


02.07 Determination of the hydration enthalpy of an electrolyte

Principle and tasksWhen a solid electrolyte dissolves inwater, a positive or negative heateffect occurs as a result of thedestruction of the crystal lattice andthe formation of hydrated ions. Theenthalpy of hydration of coppersulphate can be calculated from thedifferent heats of reaction measuredwhen anhydrous and hydrated cop-per sulphate are separately dissolvedin water.

Temperature-time curves of solution of anhydrous and hydrated copper sul-phate and determining the heat capacity of the system.

Cobra3 Basic-Unit, USB 12150.50 1Power supply 12V/2A 12151.99 1Temperature measuring module Pt100 12102.00 1Software Cobra 3 Temperature 14503.61 1Temperature probe Pt100 11759.01 1Calorimeter, transparent 04402.00 1Heating coil with sockets 04450.00 1Work and power meter 13715.93 1Universal power supply 13500.93 1Connection cable, l = 500 mm, black 07361.05 4Magnetic heating stirrer 35720.93 1Magnetic stirrer bar, l = 30 mm, oval 35680.04 1Separator for magnetic bars 35680.03 1Support rod, l = 500 mm, M10 thread 02022.20 1Right angle clamp 37697.00 1Universal clamp 37715.00 1Precision balance CPA 6202S (6200 g/0.01 g),set with software 49226.88 1Mortar with pestle, 190 ml 32604.00 1Porcelain dish, 115 ml, do = 100 mm 32518.00 1Crucible tongs, 200 mm 33600.00 1Tripod, d = 140 mm, h = 240 mm 33302.00 1Wire gauze, 160�160 mm 33287.01 1Butane burner 32178.00 1Butane cartridge 47535.00 1Glass beaker, 50 ml, tall 36001.00 2Spoon 33398.00 1Powder funnel, do = 100 mm 34472.00 1Stop watch, digital, 1/100 s 03071.01 1Wash bottle, 500 ml 33931.00 1Desiccator 34126.00 1Porcelain plate for desiccators 32474.00 1Silicone grease, 100 g, 1 tube 31863.10 1Silica gel, orange, granulated, 500 g 30224.50 1Copper(II) sulphate, anhydride, 250 g 31495.25 1Copper(II) sulphate, 250 g 30126.25 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:

Determination of the hydration enthalpyof an electrolyte P3020711



� Integral enthalpy of solution� Hess’ law� Ion solvation� Calorimetry� Heat capacity

LEC_1 05.06.2008 21:34 Uhr Seite 28


Determination of the enthalpy of neutralisation 02.08


Principle and tasksWhen a strong acid is neutralisedwith a strong base in dilute solution,the same amount of heat is alwaysreleased. If the reaction takes placeunder isobaric conditions, this heat isknown as the enthalpy of neutrali-sation. The chemical reaction whichgenerates this heat is the reaction ofprotons and hydroxyl ions to formundissociated water.

The temperature change during theneutralisation of a potassium hy-droxide solution with a hydrochloricacid solution is measured and theenthalpy of neutralisation is calcu-lated.

Temperature-time curve of neutralisation and determining the heat capacityof the system.

� Enthalpy of neutralisation� Calorimetry� Heat capacity

Cobra3 Basic-Unit, USB 12150.50 1Power supply 12V/2 A 12151.99 1Temperature measuring module Pt100 12102.00 1Software Cobra3 Temperature 14503.61 1Temperature probe Pt100 11759.01 1Calorimeter, transparent 04402.00 1Delivery pipette, 50 ml 04402.10 1Pipettor 36592.00 1Rubber bulb, double 39287.00 1Pinchcock, w = 15 mm 43631.15 1Heating coil with sockets 04450.00 1Work and power meter 13715.93 1Universal power supply 13500.93 1Connection cable, l = 500 mm, black 07361.05 4Magnetic heating stirrer 35720.93 1Magnetic stirrer bar, l = 30 mm, oval 35680.04 1Separator for magnetic bars 35680.03 1Support rod, l = 500 mm, M10 thread 02022.20 1Right angle clamp 37697.00 2Universal clamp 37715.00 2Precision balance CPA 6202S (6200 g/0.01 g),set with software 49226.88 1Volumetric flask, 500 ml 36551.00 2Glass beaker, 100 ml, tall 36002.00 1Glass beaker, 600 ml, tall 36006.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Stop watch, digital, 1/100 s 03071.01 1Wash bottle, 500 ml 33931.00 1Potassium hydroxide for 1 l of 1 M solution, ampoule 31425.00 1Hydrochloric acid for 1 l of 1 M solution, ampoule 30271.00 1Water, distilled, 5l 31246.81 1PC, Windows® 95 or higher

What you need:

Determination of the enthalpy of neutralisationP3020811


LEC_1 05.06.2008 21:34 Uhr Seite 29


02.09 Determination of the melting enthalpy of a pure substance

Principle and tasksWhen a solid melts, energy is re-quired for the destruction of thecrystal lattice. A substance whosemelting point lies slightly belowroom temperature is first cooleduntil it solidifies and then melted ina calorimeter. The melting enthalpyis calculated from the decrease intemperature due to the melting pro-cess which is measured in thecalorimeter.

Temperature-time curve for the melting process of dioxan and determiningthe heat capacity of the system.


















Test tube, 30/200 mm, Duran, PN 29 36294.00 2

Rubber stopper 32/30 39258.00 2

Dewar vessel, 500 ml 33006.00 1





1,4-Dioxan, 1000 ml 31266.70 1



What you need:

Determination of the melting enthalpyof a pure substance P3020911



� Melting point and meltingenthalpy

� Latent heat� Gibbs’ phase rule� Calorimetry� Heat capacity

LEC_1 05.06.2008 21:34 Uhr Seite 30


Boiling point elevation 02.10


Principle and tasksThe boiling point of a solution is al-ways higher than that of the puresolvent. The dependence of the tem-perature difference (elevated boilingpoint) on the concentration of thesolute can be determined using asuitable apparatus.

Measuring the increase in boilingpoint of water as a function of theconcentration of table salt, urea andhydroquinone the molar mass of thesolute can be determined.

Boiling point increase as a function of concentration of table salt in anaquous solution.

� Raoult’s law� Henry’s law� Ebullioscopy� Gibbs-Helmholtz equation

Apparatus for elevation of boiling point 36820.00 1

Temperature meter, digital, 4-2 13617.93 1

Temperature probe, immersion type Pt100, Teflon 11759.04 1

Heating hood, 250 ml 47550.93 1

Clamp for heating hood 47557.01 1


Flask, round, 250 ml, GL 25/12 35812.15 1


Jointing, GL 25/8 41242.03 1





Mortar with pestle, 190 ml 32604.00 3

Pinchcock, w = 15 mm 43631.15 1

Microspoon 33393.00 1

Pellet press for calorimeter 04403.04 1



Funnel, glass, d0 = 80 mm 34459.00 1




Beads, 200 g 36937.20 1

What you need:


Sodium chloride, 500 g 30155,50 1

Urea, pure, 250 g 30086.25 1

Hydroquinone, 250 g 30089.25 1

Glycerine, 250 ml 30084.25 1


Parallel vice

Boiling point elevation P3021001

LEC_1 05.06.2008 21:34 Uhr Seite 31


02.11 Freezing point depression

Principle and tasksThe freezing point of a solution islower than that of the pure solvent.The depression of the freezing pointcan be determined experimentallyusing a suitable apparatus (cryos-copy). If the cryoscopy constants ofthe solvent are known, the molecularmass of the dissolved substances canbe determined.

Cooling curve of a water/table salt mixture.

Apparatus for freezing point depression 36821.00 1

Gasket for GL 25, 12 mm hole 41243.03 1

Temperature meter digital, 4-2 13617.93 1

Temperature probe, Pt100 11759.01 2

Protective sleeves for temperature probe 11762.05 1


Magnetic stirrer bar, l = 30 mm 46299.02 1






Pipettor 36592.00 1





Mortar with pestle, 70 ml, porcelain 32603.00 2


Spoon 33398.00 1

Funnel, plastic, do = 50 mm 36890.00 1



Glass rod, l = 300 mm, d = 8 mm 40485.06 1


Sodium chloride, 500 g 30155.50 1

Hydroquinone, 250 g 30089.25 1

Raw alcohol for burning, 1000 ml 31150.70 1


What you need:

Freezing point depression P3021101



� Raoult’s law� Cryoscopy� Chemical potential� Gibbs-Helmholtz equation� Van’t Hoff factor

LEC_1 05.06.2008 21:34 Uhr Seite 32


Determination of the enthalpy of combustion with a calorimetric bomb 02.14


Principle and tasksThe calorimetric bomb is used tocompletely burn substances in ex-cess oxygen. The heat of combustionreleased is absorbed by the calori-metric vessel in which the bomb isimmersed, and results in a tempera-ture increase �T. The heat capacityof the system is first determined byadding a defined amount of heatfrom the combustion of benzoic acid.Subsequently, under the same condi-tions the combustion enthalpy ofnaphthalene is determined.

Determining the corrected temperature difference.

� 1st law of thermodynamics� Hess’ law � Enthalpy of combustion� Enthalpy of formation� Heat capacity

Calorimetric bomb 04403.00 1

Test vessel for calorimeter bomb 04403.03 1

Pressure tube with fittings 39299.00 1








Temperature probe, Pt100 11759.01 1

Power supply, universal 13500.93 1

Connecting cord, l = 750 mm, black 07362.05 2

Steel cylinder oxygen, 2 l, filled 41778.00 1

Reducing valve for oxygen 33482.00 1






Mortar with pestle, 70 ml, porcelain 32603.00 1


Graduated vessel, 1 l, with handle 36640.00 1




Funnel, plastic, do = 50 mm 36890.00 1


Iron wire, d = 0.2 mm, l = 100 m 06104.00 1

What you need:


Benzoic acid, 100 g 30251.10 1

Naphthalene white, 250g 48299.25 1


Determination of the enthalpy of combustionwith a calorimetric bomb P3021401

LEC_1 05.06.2008 21:34 Uhr Seite 33


02.15 Determination of the heat of formation for water

Principle and tasksThe standard molar enthalpy of for-mation is defined as the heat of re-action occurring in the direct forma-tion of one mole of the pertinentpure substance from the stable pureelements at constant pressure. Forthe conversion of hydrogen and oxy-gen to water, standard enthalpies offormation can be measured directlyusing calorimetry.

High voltage supply unit, 0-10 kV 13670.93 1Connecting cord, 30 KV, l = 1000 mm 07367.00 2Glass jacket 02615.00 1Calorimeter insert for glass jacket 02615.01 1Lid for calorimeter insert 02615.02 1Gas syringe, 100 ml, with 3-way cock 02617.00 3Gas syringe holder with stop 02058.00 3Silicone tubing, di = 7 mm 39296.00 1H-base -PASS- 02009.55 1Support rod, l = 250 mm 02031.00 2Support rod, l = 500 mm 02032.00 1Support rod, l = 750 mm 02033.00 1Right angle clamp 37697.00 10Universal clamp 37715.00 3Weather monitor, LCD 87997.10 1Laboratory thermometer –10...+50 C 38034.00 2Magnifying glass, 10�, d = 23 mm 64598.00 1Magnetic stirrer bar, l = 30 mm 46299.02 1Magnet, d = 10 mm, l = 200 mm 06311.00 1Funnel, glass, do = 55 mm 34457.00 1Graduated vessel, 1 l, with handle 36640.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Steel cylinder hydrogen, 2 l, filled 41775.00 1Steel cylinder oxygen, 2 l, filled 41778.00 1Reducing valve for hydrogen 33484.00 1Reducing valve for oxygen 33482.00 1Table stand for 2 l steel cylinders 41774.00 2Wrench for steel cylinders 40322.00 1Rubber tubing, di = 6 mm 39282.00 3Water, distilled, 5 l 31246.81 1

What you need:

Determination of the heat of formationfor water P3021501



� 1st law of thermodynamics� Calorimetry� Enthalpy of reaction � Enthalpy of formation

LEC_1 05.06.2008 21:34 Uhr Seite 34


Determination of the heat of formation for CO2 and CO (Hess’ law) 02.16


Principle and tasksThe standard molar enthalpy of for-mation is defined as the heat of re-action occurring in the direct forma-tion of one mole of the pertinentpure substance from the stable pureelements at constant pressure. Forthe conversion of carbon and oxygento CO2, the standard enthalpies offormation can be determined usingcalorimetry. The enthalpies of reac-tion for the combustion of carbonand carbon monoxide are measuredand the enthalpy of formation of CO2

is calculated using Hess` law.

� 1st law of thermodynamics� Hess’ law� Calorimetry� Enthalpy of reaction � Enthalpy of formation

Glass jacket 02615.00 1Calorimeter insert for glass jacket 02615.01 1Combustion lance for gases 02613.00 1Gasometer, 1000 ml 40461.00 1Retort stand, h = 750 mm 37694.00 2H-base -PASS- 02009.55 1Support rod, l = 250 mm 02031.00 2Barrel base -PASS- 02006.55 1Right angle clamp 37697.00 6Universal clamp 37715.00 7Magnetic stirring bar, l = 30 mm 46299.02 1Magnet, d = 10 mm, l = 200 mm 06311.00 1Weather monitor, LCD 87997.10 1Laboratory thermometer -10... +50°C 38034.00 2Magnifying glass, 10�, d = 23 mm 64598.00 1Funnel, glass, do = 55 mm 34457.00 1Graduated vessel,1 l , with handle 36640.00 1Paper, ceramic fibre 1.0�500�2000 mm 38750.01 1Commercial weight, 500 g 44096.50 1Stopcock, 3-way, T-shaped, glass 36731.00 1Test tube GL25/8, with olive 36330.15 1Glass tubes, right-angled 36701.59 1Pinchcock, w = 15 mm 43631.15 1Funnel for gas generator, 50 ml, GL18 35854.15 1Flask, round, 1-neck, 100 ml, GL25/12 35841.15 1U-tube, 2 side tubes, GL25/8 36959.15 1Test tube,180�20 mm, PN19 36293.00 1Rubber stopper, d = 22/17 mm 39255.00 1Rubber stopper, d = 38/31 mm, 1 hole 15 mm 39260.19 1Test tube holder, d = 22 mm 38823.00 1Teclu burner, natural gas 32171.05 1Safety gas tubing 39281.10 1Hose clip, d = 12… 20 mm 40995.00 2Lighter for natural / liquified gases 38874.00 1

What you need:


Steel cylinder oxygen, 2 l, filled 41778.00 1Reducing valve for oxygen 33482.00 1Wrench for steel cylinders 40322.00 1Table stand for 2 l steel cylinders 41774.00 1Hose clip, d = 8…12 mm 40996.01 4Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Mortar with pestle, 150 ml, porcelain 32604.00 1Scissors, straight, blunt, l = 140 mm 64625.00 1Tweezers, straight, blunt, l = 200 mm 40955.00 1Water jet pump 02728.00 1Rubber tubing, di = 6 mm 39282.00 5Protective glasses, green glass 39317.00 1Quartz glass wool, 10 g 31773.03 1Charcoal, small pieces, 300 g 30088.30 1Formic acid 98-100%, 250 ml 30021.25 1Sulphuric acid, 95-98%, 500 ml 30219.50 1Sodium hydroxide, flakes, 500 g 30157.50 1Glycerol, 250 ml 30084.25 1Water, distilled, 5 l 31246.81 1

Determination of the heat of formation for CO2and CO (Hess law) P3021601

LEC_1 05.06.2008 21:34 Uhr Seite 35


02.17 Determination of the calorific value for heating oil and the gross calorific value for olive oil

Principle and tasksThe heat of reaction generated dur-ing the complete combustion of 1 kgof solid or liquid fuel is known as thecalorific value H. In the experimentcalorific value of olive oil is deter-mined. In order to ensure completecombustion, the combustion takesplace in oxygen . The heat generatedduring the combustion is absorbedby a glass jacket calorimeter ofknown heat capacity. From the tem-perature increase in the calorimeterthe calorific value of the olive oil canbe calculated.


Calorimeter insert for glass jacket 02615.01 1

Combustion lance for gases 02613.00 1

H-base -PASS- 02009.55 1

Support Support rod, l = 500 mm 02032.00 1



Closure caps, GL 18 41220.03 1

Rubber stopper, d = 38/31 mm, 1 hole 15 mm 39260.19 1

Laboratory thermometer , -10...+50 C 38034.00 2

Magnet, d = 10 mm, l = 200 mm 06311.00 1



Graduated vessel, 1 l, with handle 36640.00 1

Glass tube, d = 10/8 mm, l = 300 mm 45125.01 1



Steel cylinder oxygen, 2 l, filled 41778.00 1

Reducing valve for oxygen 33482.00 1




Hose clip, d = 8…12 mm 40996.01 2

Teclu burner, natural gas 32171.05 1

Safety gas tubing 39281.10 1

Lighter for natural / liquified gases 38874.00 1

Hose clip, d = 12… 20 mm 40995.00 2

Crucible tongs, 200 mm, stainless steel 33600.00 1

Tweezers, straight, blunt, 200 mm 40955.00 1

Glass tube cutter 33185.00 1

What you need:

Determination of the calorific value for heating oiland the gross calorific value for olive oil P3021701



� 1st law of thermodynamics� Enthalpy of reaction� Enthalpy of combustion� Calorimetry� Heat capacity


Paper, ceramic fibre, 1.0�50�2000 mm 38750.01 1



Wood splints, l = 35 cm, d = 3 mm 39126.20 1

Protective glasses, green glass 39317.00 1

Glycerol, 250 ml 30084.25 1

Olive oil, pure, 100 ml 30177.10 1


LEC_1 05.06.2008 21:34 Uhr Seite 36


Dilatometry 02.18


Principle and tasksThe volume expansion of liquids andthe linear expansion of various ma-terials is determined as a function oftemperature. In order to investigateexpansion, pipes made of brass, steel,copper, aluminium and glass areclamped tight at one end, and waterfrom a temperature controlled bathis circulated through them. Thechange in length at various temper-atures is measured using a dilatome-ter. The measurement of the volumechange of water is achieved using aflat-bottomed flask with a graduatedupright pipe which is located in atemperature controlled bath (pyc-nometer).

Lenght change �l of the copper pipe as a function of temperature.

� Linear thermal expansion� Volume expansion� Heat capacity� Lattice potential

Dilatometer with clock gauge 04233.00 1

Copper tube 04231.05 1

Aluminium tube 04231.06 1





Syringe, 1 ml 02593.03 1

Cannula, 0.6�60 mm 02599.04 1


Flask, flat bottom, 100 ml, IGJ 19/26 35811.01 1

Measuring tube, l = 300 mm, IGJ 19/26 03024.00 1





Hose clip, d = 8…12 mm 40996.01 6



What you need:

DilatometryP3021801

Volume of water as a function of temperature.


LEC_1 05.06.2008 21:34 Uhr Seite 37

38

LEC_1 05.06.2008 21:34 Uhr Seite 38

Contents

LEC 03.01 Evaporative equilibrium

LEC 03.02 Vapour pressure of mixtures of ideal fluids

LEC 03.04 Boiling point diagram of a binary mixture

LEC 03.05 Solubility diagram of two partially miscible liquids

LEC 03.06 Miscibility gap in a ternary system

LEC 03.07 Distribution equilibrium

LEC 03.08 Solubility product

LEC 03.09 Dissociation equilibrium

LEC 03.10 Complex formation equilibrium

LEC 03.11 Dissociation constants

LEC 03.13 The melting point of a binary system

LEC 03.14 Law of integral ratio of volumes

LEC 03.15 Determination of the number of theoretical trays in a distillation column

LEC 03.16 Fractional distillation with the bubble tray column

LEC 03.17 Chromatographic separation procedures: gas chromatography

Chemical Equilibrium3

LEC_1 05.06.2008 21:34 Uhr Seite 39


03.01 Evaporative equilibrium

Principle and tasksFor each temperature a specificvapour pressure establishes above aliquid. If the external pressure is lo-wered by drawing off the gas phase,the equilibrium re-establishes itselfthrough evaporation of a part of theliquid phase.

The enthalpy of vaporisation of ace-tone is determined by measuring thevapour pressure at different temper-atures.

Plot of the logarithm of the vapour pressure against the reciprocaltemperature.

Calorimeter, transparent 04402.00 1Temperature meter, digital, 4-2 13617.93 1Temperature probe, immersion type, Pt100 11759.01 2Protective sleeve for immersion probe 11762.05 1Barometer / Manometer, hand-held 07136.00 1Pressure sensor 07136.01 1Tubing adapter, 3-5 / 6-10 mm 47517.01 1Silicone tubing, di = 7 mm 39296.00 1Silicone tubing, di = 2 mm 39298.00 1Retort stand, h = 750 mm 37694.00 2Right angle clamp 37697.00 3Universal clamp 37715.00 3Round flask, 100 ml, 1� GL 25/8, 2� GL 25/12 35677.15 1Jointing for connecting caps, GL 25/8 41242.03 1Glass tube, straight, l = 80 mm 36701.65 1One-way stopcock, straight 36705.00 1Security bottle with manometer 34170.88 1Water jet pump 02728.00 1Rubber tubing, vacuum, di = 6 mm 39286.00 3Hose clip, d = 12–20 mm 40995.00 2Graduated cylinder, 50 ml 36632.00 1Funnel, glass, do = 55 mm 34457.00 1Glass rod, d = 8 mm, l = 8 mm 40485.06 1Graduated vessel with handle, 1 l 36640.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Acetone, 250 ml 30004.25 1Glycerine, 250 ml 30084.25 1Sodium chloride, chem. pure, 500 g 30155.50 1IceWater

What you need:

Evaporative equilibrium P3030101

Chemical equilibrium LEC 03


� Vapour pressure� Enthalpy of vaporization� Clausius-Clapeyron equation� Trouton-Pictet rule

LEC_1 05.06.2008 21:34 Uhr Seite 40


Vapour pressure of mixtures of ideal fluids 03.02

LEC 03 Chemical equilibrium

Principle and tasksAccording to Raoult’s law, the vapourpressures of ideal solutions is thesum of the partial pressures of theindividual components. Mixtures ofbenzene and toluene show an almostideal behaviour. The vapour pressuresof benzene, toluene and differentcompositions of them are measuredwith a digital manometer underisothermal conditions.

Vapour pressure curve of the benzene/toluene system.

� Vapour pressure� Raoult’s law� Partial pressure

Barometer / Manometer, hand-held 07136.00 1Pressure sensor 07136.01 1Tubing adapter, 3-5 / 6-10 mm 47517.01 1Silicone tubing, di = 7 mm 39296.00 1Silicone tubing, di = 2 mm 39298.00 1Immersion thermostat, 100°C 08492.93 1Accessory set for immersion thermostat 08492.01 1Bath for thermostat, 6 l, Makrolon 08487.02 1H-base -PASS- 02009.55 1Support rod, l = 750 mm 02033.00 2Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 4Universal clamp 37715.00 4Round bottom flask, 100 ml, 2-neck, IGJ 19/26 35842.05 3Stopper, IGJ 19/26, glass, clear 41252.10 1Connecting tube, IGJ 19/26 – GL 18/8 35678.01 1Glass tube, right-angled, 85+60 mm 36701.52 1Glass tube, right-angled, 230 + 55 mm 36701.59 1Stopcock, 3-way, T-shaped, capillary 36732.00 1Security bottle with manometer 34170.88 1Water jet pump 02728.00 1Volumetric pipette, 50 ml 36581.00 2Volumetric pipette, 25 ml 36580.00 2Volumetric pipette, 10 ml 36578.00 2Pipettor 36592.00 1Pipette dish 36589.00 1Rubber tubing, vacuum, di = 6 mm 39286.00 2Rubber tubing, di = 6 mm 39282.00 4Hose clip, d = 8…12 mm 40996.01 4Benzene, pure, 500 ml 30038.50 1Toluene, pure, 250 ml 30236.25 1Silicone grease, 100 g, 1 tube 31863.10 1

What you need:

Vapour pressure of mixtures of ideal fluids P3030250


LEC_1 05.06.2008 21:34 Uhr Seite 41


03.04 Boiling point diagram of a binary mixture

Principle and tasksA boiling point diagram shows theboiling points of a binary mixture asa function of the vapour/liquid equi-librium of the mixture at constantpressure.

The boiling points of various mix-tures of methanol and chloroformare measured and the composition ofthe liquid phases are determinedusing refractometry and a calibrationcurve.

Index of refraction as a function of substance concentration in methanol/chloroform mixtures.

Abbe refractometer 35912.00 1Temperature meter, digital, 4-2 13617.93 1Temperature probe, immersion type, Pt100 11759.01 2Protective sleeve for immersion probe 11762.05 1Heating hood, 100 ml 47549.93 1Clamp for heating mantle 47557.01 1Power regulator 32288.93 1Immersion thermostat, 100°C 08492.93 1Accessory set for immersion thermostat 08492.01 1Bath for thermostat, 6 l, Makrolon 08487.02 1Retort stand, h = 750 mm 37694.00 2Right angle clamp 37697.00 2Universal clamp 37715.00 2Burette clamp, roller mounting 37720.00 1Round bottom flask, 100 ml, 2-neck, IGJ 19/26 35842.05 2Dimroth cooler, IGJ 19/26 35816.05 1Column head, IGJ 19 35919.01 1Stopper, IGJ 19/26, glass, clear 41252.10 1Clamp for ground joint, plastic, IGJ 19 43614.00 3Teflon collar, IGJ 19 43616.00 1Rubber tubing, di = 6 mm 39282.00 5Hose clip, d = 8…12 mm 40996.01 10Burette, 50 ml, lateral stopcock, Schellbach lines 36513.01 2Erlenmeyer flask, 100 ml, narrow neck 36118.00 11Rubber stopper, 24/30 mm 39256.00 11Glass beaker, 100 ml, tall 36002.00 2Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Funnel, glass, do = 55 mm 34457.00 1Beads, 200 g 36937.20 1Water jet pump 02728.00 1Laboratory pencil, waterproof 38711.00 1Methanol, 500 ml 30142.50 1Chloroform, pure, 250 ml 48045.25 1Glycerine, 250 ml 30084.25 1

What you need:

Boiling point diagram of a binary mixture P3030401



� Fundamentals of distillation� Equilibrium diagram� Chemical potential� Raoult’s law

Boiling point diagram of the methanol/chloroform system.

LEC_1 05.06.2008 21:34 Uhr Seite 42


Solubility diagram of two partially miscible liquids 03.05


Principle and tasksA number of different phenol /watermixtures are prepared and heateduntil complete miscibility is achieved.Subsequently the mixtures arecooled down and the temperaturesare recorded at which turbidity, as aresult of separation, becomes visible.Plots of the separation temperatureversus the composition of the mix-tures show a separation curve.

Solubility diagram of the phenol/water system.

� Binary system� Miscibility gap� Tie line� Critical dissolution

temperature





Hose clip, d = 8…12 mm 40996.01 4

Rack for 20 test tubes 08487.03 1

Test tubes, 16/160 mm 37656.10 1

Rubber stopper, 14/18 mm 39254.00 7


Burette clamp, roller mounting 47152.01 1

Burette, 10 ml, straight stopcock, Schellbach lines 36513.01 1





Spoon 33398.00 1



Laboratory pencil, waterproof 38711.00 1

Phenol, loose crystals, pure, 100 g 30185.1 0 1

Distilled water, 5 l 31246.81 1

What you need:

Solubility diagram of two partially miscibleliquids P3030501


�°C

Wphenol

%

LEC_1 05.06.2008 21:34 Uhr Seite 43


03.06 Miscibility gap in a ternary system

Principle and tasksA number of complete miscible twocomponent mixtures are prepared toinvestigate the three component a-cetic acid/chloroform/water system.These mixtures are titrated with thethird component until a two phasesystem is formed causing turbidity.The phase diagram for the threecomponent system is plotted in atriangular diagram.

Triangular diagram of the system acetic acid/chloroform/water.





Hose clip, d = 8…12 mm 40996.01 4

Rack for 20 test tubes 08487.03 1

Test tubes, 16/160 mm 37656.10 1





Burette, 10 ml, straight stopcock, Schellbach lines 36513.01 2

Long-neck flat-bottom flask, 100 ml, SB 19 36320.00 15








Acetic acid, 99…100%, 500 ml 31301.50 1

Chloroform, pure, 250 ml 48045.25 1

Distilled water, 5 l 31246.81 1

What you need:

Miscibility gap in a ternary systemP3030601



� Three component system� Miscibility gap� Phase diagram� Gibb’s phase law

LEC_1 05.06.2008 21:34 Uhr Seite 44


Distribution equilibrium 03.07


Principle and tasksAt constant temperature and pres-sure, a dissolved substance willdistribute itself between two immis-cible liquids at a constant ratio ofconcentration. The equilibrium con-centrations in both phases can bedetermined for substances sensitiveto UV light or dyed substances byphotometric measurements in thenear UV or visible light regions of theelectromagnetic spectrum.

Relationship between extinction E and concentration CA for trans-azoben-zene in acetonitrile at � = 400 nm (�), � = 420 nm (�) and � = 440 nm (�).

� Phase equilibrium� Distribution and extraction� Nernst’s distribution law� Lambert-Beer law� Photometry

Spectrophotometer S800, 330…800 nm 35600.99 1Cells for spectrophotometer 35664.02 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Microspoon 33393.00 1Retort stand, h = 750 mm 37694.00 1Support ring, di = 80 mm 37721.01 2Right angle clamp 37697.00 2Erlenmeyer flask, 1000 ml, narrow neck 36122.00 1Erlenmeyer flask, 500 ml, narrow neck 36121.00 1Erlenmeyer flask, 250 ml, narrow neck 36124.00 1Rubber stopper, 36/44 mm 39262.00 2Rubber stopper, 29/35 mm 39259.00 2Volumetric flask, 50 ml, IGJ 12/21 36547.00 4Volumetric flask, 250 ml, IGJ 14/23 36550.00 1Funnel, glass, do = 55 mm 34457.00 1Separatory funnel, 250 ml, pear shaped 36884.00 4Separatory funnel, 1000 ml, pear shaped 35850.00 1Volumetric pipette, 10 ml 36578.00 1Volumetric pipette, 20 ml 36579.00 2Pipette dish 36589.00 1Pipettor 36592.00 1Glass beaker, 100 ml, tall 36002.00 2Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Laboratory thermometer 38034.00 1Wash bottle, 500 ml 33931.00 1trans-Azobenzene, 100 g 31064.10 1Acetonitrile, 1000 ml 30000.70 1n-Heptane, 250 ml 31366.25 1

What you need:

Distribution equilibrium P3030701

Section of the UV/VIS spectrum of trans-azobenzene in acetonitrile before(�), after single (�) and after repeated extraction (�) for total volume of n-heptane.


LEC_1 05.06.2008 21:34 Uhr Seite 45


03.08 Solubility product

Principle and tasksThe solubility of poorly soluble saltsis expressed as the solubility product,i.e. the product of the concentrationsof cations and anions in the solution,which are in equilibrium with thesolid salt. These concentrations canbe determined via conductivitymeasurements.

Digital conductivity meter, demo 13701.93 1

Conductivity / temperature probe 13701.01 1





Hose clip, d = 8…12 mm 40996.01 4



Magnetic stirrer, mini 47334.93 1


Mortar with pestle 32603.00 2

Spoon 33398.00 1




Erlenmeyer flask, 100 ml, narrow neck 36118.00 4

Powder funnel, do = 65 mm 34472.00 1


Calcium carbonate, powder, 500 g 30052.50 1

Calcium fluoride, 250 g 31175.25 1

Conductivity standard solution 47070.02 1


What you need:

Solubility productP3030801



� Solubility� Dissociation� Ionic conductivity� Ion mobility

LEC_1 05.06.2008 21:34 Uhr Seite 46


Dissociation equilibrium 03.09


Principle and tasksCarboxylic acids are potential elec-trolytes, which exist in a weaklydissociated condition in aqueoussolutions. The location of the disso-ciation equilibrium is quantitativelydescribed by the Ka or pKa value,which can be determined with po-tentiometric measurements.

Neutralisation curve of formic acid.

� True and potential electrolytes� Strong and weak acids� Law of mass action� Henderson-Hasselbalch

equation� Dissociation constant and

pKa value� Substituent effects� Potentiometry

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1pH-electrode, gel-filled, BNC 46265.10 * 1Storage flask for pH-electrodes 18481.20 1Immersion probe NiCr-Ni, Teflon, 300°C 13615.05 1Motor piston burette, 50 ml 36499.93 1Cable Chem-Unit / Motor piston burette 36501.01 * 1Rubber stopper, d = 18/14 mm, 1 hole 39254.01 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Glass beaker, 50 ml, tall 36001.00 2Glass beaker, 150 ml, tall 36003.00 1Glass beaker, 250 ml, tall 36004.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Volumetric flask, 100 ml 36548.00 6Volumetric flask, 5 ml 36577.00 6Pipettor 36592.00 1Pipette dish 36589.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Microspoon 33393.00 1Wash bottle, 500 ml 33931.00 1Buffer solution, pH 4.62, 1000 ml 30280.70 1Buffer solution, pH 9.00, 1000 ml 30289.70 1Formic acid acid 98...100%, 250 ml 30021.25 1Acetic acid 99…100%, pure, 1l 31301.70 1Monochloracetic acid, 100 g 30060.10 1Propionic acid, 500 ml 31753.50 1N-butyric acid, 100 ml 30047.10 1Lactic acid, 100 ml 30264.10 1Caustic soda solution, 0.1 M, 1000 ml 48328.70 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:


Changes in the equipment required for use of the Basic-Unit:

(instead of * above mentioned)



Data cable, RS232 14602.00 1

Measuring module, pH/Potential 12101.00 1

Measuring module, NiCr-Ni 12104.00 1

Software Cobra3 pH/Potential 14509.61 1

pH-electrode, gel-filled 18450.00 1

Cable Basic-Unit / Motor piston burette 36501.03 1

Dissociation equilibriumwith Cobra3 Basic-Unit P3030911

Dissociation equilibriumwith Cobra3 Chem-Unit P3030940

LEC_1 05.06.2008 21:34 Uhr Seite 47


03.10 Complex formation equilibrium

Principle and tasksMany metals, in particular transitionelements, can form complexes withcharged or neutral ligands. The sta-bility of these complexes is describedby the complex formation constant.In the case of the silver aminecomplex, the complex formationconstant can be determined with aprecipitation titration from a silversalt solution.

Determination of the number of ligands bound in the complex.

Burette, 25 ml, lateral stopcock, Schellbach lines 36506.01 1Burette clamp, roller mounting 37720.00 1Retort stand, h = 750 mm 37694.00 2Graduated pipette, 25 ml 36602.00 1Volumetric pipette, 5 ml 36577.00 1Volumetric pipette, 10 ml 36578.00 1Volumetric pipette, 20 ml 36579.00 2Pipettor 36592.00 1Pipette dish 36589.00 1Erlenmeyer flask, 250 ml, wide neck 36134.00 5Volumetric flask, 100 ml, IGJ 12/21 36548.00 4Volumetric flask, 250 ml, IGJ 14/23 36550.00 3Funnel, glass, do = 55 mm 34457.00 3Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Spoon 33398.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Wash bottle, 500 ml 33931.00 1Silver nitrate, cryst., 15 g 30222.00 1Potassium bromide, 100 g 30258.10 1Ammonia solution, 25%, 1000 ml 30933.70 1Water, distilled, 5 l 31246.81 1

What you need:

Complex formation equilibrium P3031001



� Complex formation� Chemical equilibrium� Equilibrium constant

LEC_1 05.06.2008 21:34 Uhr Seite 48


Dissociation constants 03.11


Principle and tasksThymol blue, a colour indicator, ispartially dissociated as a weak acidin aquous solution, whereby theionised and non-ionised formsdemonstrate absorption maxima atdifferent wavelengths in the visibleregion of the electromagnetic spec-trum. The Ka or pKa value of the indi-cators, which characterise the posi-tion of the dissociation equilibrium,can thus be advantageously deter-mined using photometric measure-ments in the visible spectral region.

Absorption spectra of thymol blue at pH = 4 (�), pH = 9 (�) and pH = 11 (�).

� Strong and weak acids� Dissociation constants and

pKa value� Henderson-Hasselbalch

equation� Lambert-Beer law� Photometry

Spectrophotometer 190 – 1100 nm 35655.93 1

Cells for spectrophotometer 35664.02 1




Volumetric flask, 50 ml, IGJ 12/21 36547.00 3

Volumetric flask, 1000 ml, IGJ 24/29 36552.00 3






Pipettor 36592.00 1





Laboratory thermometer 38034.00 1


Buffer solution pH 9.00, 1000 ml 30289.70 1

Thymol blue, indicator, powder, 5 g 31896.02 1

Hydrochloric acid, 0.1 M, 1000 ml 48452.70 1

Sodium hydroxide, 0.1 M, 1000 ml 48328.70 1

Ethanol, absolute, 500 ml 30008.50 1


What you need:

Dissociation constants P3031101


LEC_1 05.06.2008 21:34 Uhr Seite 49


03.13 The melting point of a binary system

Principle and tasksIn plotting the cooling curves ofbinary mixtures one determines thetemperatures of melting and solidi-fication of specimens with differingmolar fractions of the two compo-nents. These results are entered in atemperature versus concentrationdiagram. The composition of the eu-tectic mixture and its melting pointis determined from the melting pointdiagram.

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Thermocouple NiCr-Ni, sheathed 13615.01 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 1Universal clamp 37715.00 1Test tube, 180 mm�18 mm, 100 pcs. 37658.10 1Test tube rack, 12 holes, d = 22 mm, wood 37686.00 1Powder funnel, do = 65 mm 34472.00 1Mircospoon 33393.00 1Mortar with pestle, 70 ml 32603.00 2Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Teclu burner, natural gas 32171.05 1Safety gas tubing, 1 m 39281.10 1Hose clips, d = 12...20 mm 40995.00 2Lighter for natural / liquified gases 38874.00 1Napththalene, white, 250 g 48299.25 1Biphenyl, 100 g 31113.10 1Standard petrol, b.p. 65-95°C, 1000 ml 31311.70 1PC, Windows® 95 or higher

What you need:



� Melting point� Binary system� Eutectic mixture� Gibbs‘ phase law

Cooling curve of a misture of naphthalene and biphenyl.

Changes in the equipment required for use of the Basic-Unit:(instead of * above mentioned)Cobra3 Basic-Unit, USB 12150.50 1Measuring module, Temperature 12104.00 1Software Cobra3 Temperature 14503.61 1

The melting point of a binary systemwith Cobra3 Basic-Unit P3031311

The melting point of a binary systemwith Cobra3 Chem-Unit P3031340

LEC_1 05.06.2008 21:34 Uhr Seite 50


Law of integral ratio of volumes 3.14


Principle and tasksAccording to Gay-Lussac’s law ofchemical volumes, gases react in vol-ume ratios which are whole num-bers. The volume ratio for the con-version of hydrogen with oxygen towater is experimentally determinedby burning gas mixtures of differentcompositions and measuring the re-sulting gas volume.

Dependence of the final volume V1 reduced to room temperature from the ini-tial volume Vo of hydrogen-oxygen mixtures of different composition.

� Law of constant proportions� Avogadro’s law� General equation of state for

ideal gases� Gay-Lussac’s law

Slow eudiometer 02612.00 1Glass jacket 02615.00 1Heating apparatus 32246.93 1Power regulator 32247.93 1High voltage power supply, 0…10 kV 07367.00 2Connecting cord, 30 kV, l = 1000 mm 07367.00 2Digital thermometer 07050.00 1Immersion probe, NiCr-Ni 13615.03 1Glass tubes, straight, l = 80 mm 36701.65 1H-base -PASS- 02009.55 1Support rod, l = 250 mm 02031.00 2Right angle clamp 37697.00 2Universal clamp 37715.00 2Magnet, l = 200 mm, d = 10 mm 06311.00 1Magnetic stirrer bar, l = 30 mm 46299.02 1Glass beaker, 250 ml, tall 36004.00 1Funnel, glass, do = 55 mm 34457.00 1Syringe, 50 ml 02592.00 1Cannula, 0.45�13 mm 02598.04 1Closure caps, GL 18 41220.03 1Rubber caps 02615.03 1Rubber tubing, di = 6 mm 39282.00 1Silicone tubing, di = 7 mm 39296.00 1Gas bar 40466.00 1Graduated vessel, with handle 36640.00 1Reduction valve for hydrogen 33484.00 1Reduction valve for oxygen 33482.00 1Steel cylinder, hydrogen, 2 l, filled 41775.00 1Steel cylinder, oxygen, 2 l, filled 41778.00 1Table stand for 2 l steel cylinders 41774.00 2Wrench for steel cylinder 40322.00 1Silicone fluid for heating bath, 500 ml 31849.50 1Water

What you need:

Law of integral ratio of volumesP3031401


LEC_2 05.06.2008 18:32 Uhr Seite 51


03.15 Determination of the number of theoretical trays in a distillation column

Principle and tasksThe separation power of a rectifica-tion column can be determined withan appropriate binary mixture,whose equilibrium composition ismeasured in the distillation flask andin the domed glass head of the dis-tillation apparatus. The number oftheoretical trays can be numericallyor graphically obtained from themeasured values.

Equilibrium diagram.

Distillation system, without silvering 35917.88 1

Rack-system for distillationsapparatus 35917.00 1

Distilling flask, 6000 ml, 4 � IGJ 29 35873.00 1

Heating mantle for roundbottom flask, 6000 ml 49546.93 1



Software temperature meter 4-2 14405.61 1

Data cable, plug/socket, 9 pole 14602.00 1

Temperature probe, immersion type, Pt100 11759.01 1

Temperature probe, immersion, Pt100, teflon 11759.04 3

Abbe refractometer 35912.00 1

Immersion thermostat C10 08492.93 1

Accessory set for C10 thermostat 08492.01 1

Bath for thermostat, Makrolon 08487.02 1

Rubber tubing, i.d. = 6 mm 39282.00 4

Hose clamp for 5-12 mm diameter 40997.00 6

Hose clamp for 10-17 mm diameter 40998.00 2

Rubber caps, 10 pcs 39275.03 1

Pasteur pipettes, 250 pcs 36590.00 1

Set of Precision Balance Sartorius CPA 623S and measure software balances 49224.88 1

Snap-cap vials, d = 30 mm, h = 50 mm, 10 pcs 33624.03 2

Graduated cylinder 1000 ml 36632.00 1

Funnel, glass, top diameter 150 mm 34461.00 1

Stop clock, demonstration, diameter 13 cm 03075.00 1

What you need:



� Bubble tray column� Number of theoretical trays� Rectification� Raoult’s law� Boiling-point diagram

Boiling Stones, 200 g 36937.20 1

n-Heptane, 1000 ml 31366.70 1

Methylcyclohexane, 1 l 31566.70 3


Determination of the number of theoreticaltrays in a distillation column P3031501

LEC_2 05.06.2008 18:32 Uhr Seite 52


Fractional distillation with the bubble tray column 03.16


Principle and tasksIn countercurrent distillation (rectifi-cation) using a column, the risingvapour can enter into interactionswith the condensate. In this manner,a fractional distillation, i.e. a distilla-tion in several steps for the separa-tion of substances with similar boil-ing points, can be performed in a sin-gle apparatus. If bubble tray columnsare used condensate can be removedfrom the individual bubble trays. Thesump product, the head products andthe condensates of both trays are ex-amined and compared gas chro-matographically.

Temperature-time curve for a fractional distilla-tion.

� Bubble tray column� Rectification� Continuous and discontinuous

distillation� Gas chromatography

Cobra3 Chem-Unit 12153.00 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 1Immersion probe NiCr-Ni, Teflon 13615.05 3Temperature probe, Pt1000 12123.00 1Protective sleeve for temperature probe, l = 160 mm 11762.05 1Heating hood, 250 ml 47550.93 1Support clamp for heating hood 47557.01 1Power regulator 32247.93 1H-base -PASS- 02009.55 2Support rod, l = 1000 mm 02034.00 2Support rod, l = 750 mm 02033.00 2Support rod, l = 250 mm 02031.00 1Retort stand, h = 500 mm 37692.00 1Right angle clamp 37697.00 14Universal clamp 37715.00 12Bubble tray column, GL25/12 35914.15 1Round bottom flask, two-necked, 250 ml, GL 25/12, GL 18/8 35843.15 1Adapter, IGJ 19 / GL tube d = 12 mm 35800.05 1Column head with stopcock, IGJ 19 35919.01 1Dimroth condenser, IGJ 19 35816.05 1Glass tube, straight, d = 8 mm, l = 250 mm 36701.68 1Cooling jacket, GL 25/8 34880.01 1Dropping funnel with stopcock, 50 ml, GL 18 35853.15 1Connecting caps, GL18 41230.03 1Gasket for GL 18, 8 mm hole 41240.03 1Ground joint collar, PTFE, IGJ 19 43616.00 1Ground joint clamp, IGJ 19 43614.00 2Control unit for gas chromatography 36670.99 1Measuring probe for gas chromatography 36670.10 1Glass jacket 02615.00 1Gas separation column 36670.00 1Rubber caps 02615.03 1Glass tube, straight, l = 80 mm 36701.65 1Soap bubble flow meter 36675.00 1Microliter syringe, 10 ml 02607.00 1Connecting cable, l = 250 mm, red 07360.01 1Connecting cable, l = 250 mm, blue 07360.04 1Laboratory thermometer, -10…+100°C 38056.00 1Stop watch, digital, 1/100 s 03071.01 1Steel cylinder, helium, 2 l, filled 41776.00 1

What you need:


Table stand for 2 l gas cylinder 41774.00 1Reducing valve for helium 33481.00 1Wrench for steel cylinders 40322.00 1Immersion thermostat, 100°C 08492.93 1Accessory set for immersion thermostat 08492.01 1Bath for thermostat, 6 l, Makrolon 08487.02 1Rubber tubing, vacuum, di = 6 mm 39286.00 2Rubber tubing, di = 6 mm 39282.00 10Hose clip, d = 8…12 mm 40995.01 4Hose clip, d = 12…20 mm 40996.01 10Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Round bottom flask, 500 ml, IGJ 29/32 35862.00 1Adapter, IGJ 29 to GL 18/8 35678.02 1Ground joint collar, IGJ 29 43617.00 1Glass stopper, IGJ 29/32 41256.10 1Trough, 150�150�65 mm 33928.00 1Water jet pump 02728.00 1Security bottle with manometer 34170.88 1Spoon with spatula end, l = 150 mm 33398.00 1Funnel, glass, do = 55 mm 34457.00 1Funnel, glass, do = 80 mm 34459.00 1Snap-cap vials 33621.03 2Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Graduated cylinder, 100 ml 36629.00 1Glass beaker, 150 ml, tall 36003.00 2Glass beaker, 250 ml, tall 36004.00 1Stirring rod, glass 40485.03 1Laboratory pencil, waterproof 38711.00 1Silicone grease, 100 g, 1 tube 31863.10 1Beads, 200 g 36937.20 1Quartz glass wool, 10 g 31773.03 1Chromosorb, PAW, 80/100 mesh, 20 g 31514.04 1Dinonylphthalate, 100 ml 31276.10 1Acetone, 250 ml 30004.25 1n-Pentane, 250 ml 31707.25 1n-Hexane, 250 ml 31369.25 1n-Heptane, 250 ml 31366.25 1Water, distilled, 5 l 31246.81 2Soap solution • Drying oven • PC, Windows 95 or higher

Fractional distillation with the bubbletray column P3031640

Gas chromatographic separation of the mixturefrom the tray 1.

LEC_2 05.06.2008 18:32 Uhr Seite 53


03.17 Chromatographic separation procedures: gas chromatography

Principle and tasksChromatographic procedures allow aseparation of substance mixtures withthe aid of a stationary separation phaseand a mobile phase. In gas chromato-graphy the mobile phase is a gas whichtransports the substance through theseparation column at a constant flowrate. The establishment of equilibriabetween the stationary phase and thedifferent substances results in differ-ent migration rates of the individualcomponents. At the end of the columna thermal conductivity cell detects thedifferent substances on the basis oftheir differing thermal conductivities.

A mixture of butane gases and a two-component mixture consisting ofethanol and ethyl acetate are separat-ed and identified chromatographically.

Gas chromatographic separation of a mixture of butane gases.

Cobra3 Chem-Unit 12153.00 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 1Connecting cable, l = 250 mm, red 07360.01 1Connecting cable, l = 250 mm, blue 07360.04 1Control unit for gas chromatography 36670.99 1Measuring probe for gas chromatography 36670.10 1Glass jacket 02615.00 1Gas separation column 36670.00 1Rubber caps 02615.03 1Soap bubble flow meter 36675.00 1H-base -PASS- 02009.55 1Support rod, l = 750 mm 37692.00 2Right angle clamp 37697.00 6Universal clamp 37715.00 6Microliter syringe, 10 ml 02607.00 1Syringe, 1 ml 02593.03 1Cannula, 0.45 mm�12 mm 02598.04 1Glass tube, straight, l = 80 mm 36701.65 1Laboratory thermometer, -10…+100°C 38056.00 1Stop watch, digital, 1/100 s 03071.01 1Steel cylinder, helium, 2 l, filled 41776.00 1Table stand for 2 l gas cylinder 41774.00 1Reducing valve for helium 33481.00 1Wrench for steel cylinders 40322.00 1Immersion thermostat, 100°C 08492.93 1Accessory set for immersion thermostat 08492.01 1Bath for thermostat, 6 l, Makrolon 08487.02 1Rubber tubing, vacuum, di = 6 mm 39286.00 2Rubber tubing, di = 6 mm 39282.00 6Hose clip, d = 8…12 mm 40995.01 7Hose clip, d = 12…20 mm 40996.01 2Gas bar 40466.00 2Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Round bottom flask, 500 ml, IGJ 29/32 35862.00 1Adapter, IGJ 29 to GL 18/8 35678.02 1Ground joint collar, IGJ 29 43617.00 1Glass stopper, IGJ 29/32 41256.10 1Trough, 150�150�65 mm 33928.00 1Water jet pump 02728.00 1Security bottle with manometer 34170.88 1Spoon with spatula end, l = 150 mm 33398.00 1

What you need:



� Chromatography� Chromatogram� Thermal conductivity detector� Nernst’s law of distribution� Number of theoretical trays

Funnel, glass, do = 55 mm 34457.00 1Snap-cap vials 33621.03 2Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Glass beaker, 150 ml, tall 36003.00 2Laboratory pencil, waterproof 31773.03 1Fine control valve 33499.00 1Compressed gas, n-butane 41773.11 1Compressed gas, iso-butane 41773.12 1Quartz glass wool, 10 g 31773.03 1Chromosorb, PAW, 80/100 mesh, 20 g 31514.04 1Dinonylphthalate, 100 ml 31276.10 1Acetone, 250 ml 30004.25 1Ethyl alcohol, absolute, 500 ml 30008.50 1Ethyl acetate, 250 ml 30075.25 1Butane burner Labogaz 206 32178.00 1Butane cartridge C 206 47535.00 1Water, distilled, 5 l 31246.81 1Soap solution • Drying oven • PC, Windows® 95 or higher

Chromatographic separation procedures: gas chromatography P3031740

LEC_2 05.06.2008 18:32 Uhr Seite 54

Interfacial ChemistryContents

LEC 04.01 Determination of the surface tension of pure liquids with the bubble pressure method

LEC 04.02 Determining surface tension using the ring method (Du Nouy method)

LEC 04.03 Free films

LEC 04.04 Contact angle

LEC 04.06 Electrokinetic potential

LEC 04.07 Electrophoretic mobility

LEC 04.08 Adsorption isotherms4

LEC_2 05.06.2008 18:32 Uhr Seite 55


04.01 Determination of the surface tension of pure liquids with the bubble pressure method

Principle and tasksThe bubble pressure method is aprocedure for the determination ofsurface tension which is easilyperformed experimentally. A capil-lary tube is vertically immersed inthe liquid to be investigated. Thenthe pressure required to force a gasbubble out of the capillary is deter-mined. The surface tension can becalculated from the pressure in-crease, the radius of the capillarytube and its immersion depth.

Lab jack, 160�130 mm 02074.00 2

U-tube pressure gauge 03931.00 1




Capillary tube, di = 1.5 mm, l = 450 mm 05939.00 1



Aspirator bottle, clear, 1000 ml 34175.00 1

Bottle, narrow mouth, 1000 ml, clear 41104.01 1

Stopcock, 1-way, straight, glass 36705.00 1

Capillary tube, T-shaped 37030.00 2

Glass tubes, right-angled, 85�60 mm 36701.52 1

Glass tubes, right-angled, 230�55 mm 36701.59 1


Rubber stopper, d = 32/26 mm, 2 holes 39258.02 1

Rubber stopper, d = 22/17 mm, 1 hole 39255.01 1

Glass tube cutter 33185.00 1


Vernier caliper 03010.00 1

Ethylene glycol, 250 ml 30085.25 1



Hydrochloric acid 37%, 1000 ml 30214.70 1

Nitric acid , 65%, 1000 ml 30213.70 1


What you need:

Determination of the surface tension of pureliquids with the bubble pressure method P3040101

Interfacial Chemistry LEC 04


� Interfacial surface tension� Interfacial surface energy� Hydrostatic pressure� Intermolecular interactions

LEC_2 05.06.2008 18:32 Uhr Seite 56


Determining surface tension using the ring method (Du Nouy method) 04.02


Principle and tasksA molecule in a liquid is subject toforces exerted by all molecules sur-rounding. The resultant force actingon a molecule in a boundary layer ofa liquid surface is directed towardsthe interior of the liquid. This force ismeasured on a ring shortly before aliquid film tears using a torsionmeter. The surface tension is calcu-lated from the diameter of the ringand the tear-off force. In this exper-iment the surface tension of olive oiland water / methanol mixtures aredetermined.

Temperature dependence of surface tension of olive oil.

� Surface energy� Surface tension� Adhesion� Critical point

Torsion dynamometer, 0.01 N 02416.00 1

Surface tension measuring ring 17547.00 1



Electronic temperature control 35721.00 1

Spring balance holder 03065.20 1

Support rod with hole, l = 100 mm 02036.01 1






Cristallizing dish, 1000 ml 46245.00 2

Cristallizing dish, 560 ml 46244.00 2

Silk thread, l = 200 m 02412.00 1

Glass tubes, straight, l = 150 mm 36701.64 1

Stopcock, 1-way, straight, glass 36705.00 1




Pipettor 36592.00 1







What you need:

Determining surface tension using thering method (Du Nouy method) P3040201

Surface tension of water/ethanol mixtures as a function of ethanol concen-tration.


c

vol % ethanol

�

°C

LEC_2 05.06.2008 18:32 Uhr Seite 57


04.03 Free films

Principle and tasksIf a platinum wire ring is drawnthrough an aqueous tenside solutiona tubular film is formed of water,whose boundaries to the air aremade up of tenside membranes. Thefilm comprises an aqueous elec-trolyte solution sandwiched betweentwo monomolecular membranes oflauryl sulphate ions. Its thickness canbe estimated by measuring the con-ductivity, provided that the specificconductivity of the electrolyte andthe geometry of the film are known.

Digital conductivity meter 13701.93 1Conductivity/temperature electrode 13701.01 1Adapter conductivity cells 13701.02 1Platinum electrode in protective tube, l = 8mm 45206.00 1Platinum wire, d = 0.3 mm, l = 100 mm 31739.03 1Connecting cord, l = 500 mm, yellow 07361.02 2H-base -PASS- 02009.55 1Support rod, l = 500 mm 02032.00 2Right angle clamp 37697.00 3Universal clamp 37715.00 3Support rod with hole, l = 100 mm 02036.01 1Spring balance holder 03065.20 1Slide mount 08286.05 1Round flask, 100 ml, 3-neck, GL25 / 2 GL18 35677.15 1Closure caps, GL25 41221.03 1 Rubber tubing, di = 4 mm 39280.00 1Volumetric flask 500 ml, IGJ19/26 36551.00 1Funnel, glass, do = 55 mm 34457.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Glass beaker, 100 ml, tall 36002.00 2Spoon 33398.00 1Microspoon 33393.00 1Wash bottle, 500 ml 33931.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Standard solution 1413 µS/ cm, 460ml 47070.02 1Sodium chloride, 500 g 30155.50 1Sodium dodec. hydrogen sulphate, 100 g 31280.10 1Water, distilled, 5 l 31246.81 1

What you need:

Free films P3040301



� Tensides � Double membrane� Surface tension� Electrolyte conductivity

LEC_2 05.06.2008 18:32 Uhr Seite 58


Contact angle 04.04


Principle and tasksThe edge of a drop of liquid forms acharacteristic angle on a solid sur-face . The Wilhelmy method can beused to determine this boundaryangle if the surface tension of theliquid is known. The method meas-ures the increase in weight, whichoccurs when a right-angled platewith a smooth surface and knowngeometry is immersed into a solu-tion.

Plot of weight as a function of the depth of immersion.

� Contact angle� Wilhelmy equation� Surface tension� Wetting

Torsion dynamometer, 0.01 N 02416.00 1

Dial gauge 10 / 0.01 mm 03013.00 1


Lab jack, 160�130 mm 02074.00 1




Microscopic slides 64691.00 1


Scissors, straight, pointed, l = 110 mm 64623.00 1


Ethyl acetate, 250 ml 30075.25 1


Scotch tape

Thread

Paper towels

What you need:

Contact angle P3040401


LEC_2 05.06.2008 18:32 Uhr Seite 59


04.06 Electrokinetic potential

Principle and tasksAt the solid-liquid interface an elec-trokinetic potential is formed, whichresults in electrokinetic phenomena.Electro-osmosis is demonstrated ona finely particulate solid suspensionin water. On application of a highelectrical field strength a liquid cur-rent which can be detected with theaid of a precision manometer is in-duced.

Dependence of the time required to produce a pressure alternation of 0.1 hPaon the applied cell voltage.

Power supply, regulated, 0… 600 VDC 13672.93 1




U tube, 2 side tubes, GL25/8 36959.15 1

Connecting caps, GL25 41231.03 1

Gasket for GL25, 8 mm hole 41242.03 1

Platinum electrode in protection tube, l = 8 mm 45206.00 2



Precision manometer 03091.00 1




Stop watch, interruption type 03076.01 1


Spoon 33398.00 1


Silica gel 60, 0.2 - 0.5 mm, 1 kg 31507.70 1



What you need:

Electrokinetic potential P3040601



� Electrochemical double layer� Helmholtz (Smoluchowski)

equation� Electro-osmosis� Phase boundary

LEC_2 05.06.2008 18:32 Uhr Seite 60


Electrophoretic mobility 04.07


Principle and tasksElectrophoresis is a standard methodof modern biochemistry. It enablesthe isolation and identification ofionisable molecules according totheir differing migration rates in anelectric field, which are due to theircharges and masses.

The proteins contained in egg whiteare separated using gel electro-phoresis. By comparing the fraction-ated proteins with a reference mix-ture of proteins, their approximatemolar masses are determined.

Electrophoretic separation of egg white proteins and a reference protein mix-ture.

� Molecular and colloidsuspensions

� Amino acids and proteins� Electrophoresis and

electrochromatography� Migration rate� Electrophoretic mobility

Electrophoresis chamber, vertical 35018.20 1

Electrophoresis power supply, 100/200 V 35019.93 1

Precision balance, with data output, 320 g 48800.88 1

Reaction vials, 1.5 ml 37653.00 1

Rack for reaction vials 37652.00 1

Microlitre pipette, 2-20 µl 47141.01 1

Microlitre pipette, 25-250 µl 47141.04 1

Disposable tips, yellow 47148.01 1



Erlenmeyer flask, 1000 ml, wide neck 36133.00 1

Petri dish, d = 200 mm 64796.00 1




Glass rod, l = 300 mm, d = 8 mm 40485.06 1

Ruler, l = 200 mm 09937.01 1

Stop clock 03075.00 1

Scalpel, metal handle 64614.00 1

Protective gloves, vinyl, medium 39175.02 1

Acrylamide gel, 10 % 35018.21 1

SDS-PAGE Standards BR, 0.2 ml 35018.25 1

Tris-glycine-buffer, 10�, 1000 ml 35019.20 1

Laemmli buffer, 30 ml 35019.21 1

Coomassie brilliant blue solution, 1000 ml 35018.26 1


Chicken egg

What you need:

Electrophoretic mobility P3040701

Identification and determination of the molar masses of egg white proteins.


LEC_2 05.06.2008 18:32 Uhr Seite 61


04.08 Adsorption isotherms

Principle and tasksIn general, the term adsorption isused to describe the attachment ofgases or dissolved substances to thesurface of a solid (or liquid inter-faces). At a constant temperature,the quantity of absorbed substancesis a function of the type of systeminvestigated and the partial pressureand/or the concentration of the sub-stance in question. The residual equi-librium concentrations of citric acidare determined after stirring solu-tions of differing initial concentra-tions with a constant mass of activecarbon. Using the measured results,the adsorption isotherm is investi-gated which is valid for the givensystem.

Investigation of the adsorption isotherm for the citric acid/active carbonsystem.

Retort stand, h = 750 mm 37694.00 2Burette clamp, roller mounting 37720.00 1Filtration stand for 2 funnels 33401.88 1Magnetic stirrer, mini 47334.93 2Magnetic stirrer bar, l = 30 mm 46299.02 2Separator for magnetic bars 35680.03 1 Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1 Burette 50 ml, lateral stopcock 36513.01 1 Volumetric flask 1000 ml, IGJ 24/29 36552.00 1 Volumetric flask 250 ml, IGJ 14/23 36550.00 6 Volumetric pipette, 10 ml 36578.00 1 Volumetric pipette, 25 ml 36580.00 1 Volumetric pipette, 50 ml 36581.00 1 Volumetric pipette, 100 ml 36582.00 1 Graduated pipette, 25 ml 36602.00 1 Pipettor 36592.00 1 Pipette dish 36589.00 1 Erlenmeyer IGJ 29/32, 250 ml 46126.00 6 Stopper, PP, for IGJ 29/32 47508.00 6 Erlenmeyer flask, wide neck, 250 ml 36134.00 7Glass beaker, 100 ml, tall 36002.00 7 Funnel, glass, do = 55 mm 34457.00 7 Circular filters, d = 90 mm 32977.03 1 Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1 Spoon 33398.00 2 Wash bottle, 500 ml 33931.00 1 Citric acid, 250 g 30063.25 1 Caustic soda solution, 1.0 M, 1000 ml 48329.70 1 Phenolphthalein, 1% solution, 100 ml 31714.10 1 Activated carbon, granular, 500 g 30011.50 1 Water, distilled, 5 l 31246.81 1

What you need:

Adsorption isotherms P3040801



� Adsorption � Adsorbing agent and adsorbate� Adsorbing and adsorbed

substances� Adsorption isotherm after

Henry

Confirmation of the validity of the absorption isotherm for the citric acid/active carbon system.

LEC_2 05.06.2008 18:32 Uhr Seite 62

Chemical Kinetics5 Contents

LEC 05.01 Saponification rate of tert-butyl chloride

LEC 05.02 Reaction rate and activation energy of the acid hydrolysis of ethyl acetate

LEC 05.03 Kinetics of saccharose inversion

LEC 05.07 Halogen exchange rate

LEC 05.08 Conductometric measurements on the saponification of esters

LEC 05.09 Enzyme kinetics: Determination of the Michaelis constant

LEC 05.10 Enzyme kinetics: Inhibition and poisoning of enzymes

LEC_2 05.06.2008 18:32 Uhr Seite 63


05.01 Saponification rate of tert-butyl chloride

Principle and tasksTertiary butylhalogenides are saponi-fied in aqueous and aqueous basicsolutions according to an SN1 mech-anism to tertiary butanol. The kine-tics of the reaction can be followedvia the temporal consumption ofhydroxide ions and evaluated ac-cordingly.

The concentration-time diagram forthe saponification of tert-butyl chlo-ride with sodium hydroxide solutionis determined. Based on the experi-mental data, the valid reaction ordercan be established.

Concentration-time diagram for the saponification of tert-butyl chloride inacetone/water.

Magnetic heating stirrer 35720.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Magnetic stirrer bar, l = 50 mm 46299.03 1Support rod, l = 500 mm, M10 thread 02022.05 1Right angle clamp 37697.00 2Universal clamp 37715.00 2Burette clamp, roller mounting 37720.00 1Digital thermometer 07050.00 1Immersion probe, NiCr-Ni 13615.03 1Stop-watch, digital, 1/100 s 03071.01 1Microburette, 10 ml 36527.01 1Crystallisation dish, 1000 ml 36246.00 1Erlenmeyer flask, 250 ml, narrow neck, SB 29 36424.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1

Weighing dishes, 80�85�14 mm 45019.05 1Volumetric flask, 50 ml 36547.00 1Volumetric flask, 100 ml 36548.00 2Volumetric pipette, 10 ml 36578.00 2Volumetric pipette, 20 ml 36579.00 1Volumetric pipette, 50 ml 36581.00 2Pipettor 36592.00 1Pipette dish 36589.00 1Funnel, glass, do = 55 mm 34457.00 1Rubber stopper, 17/22 mm 39250.00 1Rubber stopper, 26/32 mm 39258.00 2Glass beaker, 50 ml, tall 36001.00 1Microspoon 33393.00 1

What you need:

Chemical Kinetics LEC 05


� Reaction rate constant� Reaction order� Rate law for first and second

order reactions

Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Wash bottle, 500 ml 33931.00 1Tert-butyl chloride, 250 ml 30045.25 1Caustic soda solution, 1.0 M, 1000 ml 48329.70 1Bromothymolblue, indicator, 1 g 31138.01 1Acetone, chem. pure, 250 ml 30004.25 1Water, distilled, 5 l 31246.81 1

Saponification rate of tert-butyl chlorideP3050101

LEC_2 05.06.2008 18:32 Uhr Seite 64


Reaction rate and activation energy of the acid hydrolysis of ethyl acetate 05.02


Principle and tasksEthyl acetate is hydrolysed in an acidsolution according to a pseudo-firstorder rate law to equivalent quanti-ties of ethanol and acetic acid. Basedon the alkalimetric determination ofthe acetic acid formed, conclusionscan be made about the temporalconcentration of ester.

The reaction rate constant for thisreaction is determined at differenttemperatures, and the activation en-ergy is calculated.

Graphic determination of the reaction rate constants for the acid hydrolysisof ethyl acetate at Tx = 299.15 K and To = 314.15 K.

� Reaction rate� Rate law for first and second

order reactions� Reactions with pseudo-order� Arrhenius equation� Activation energy





Hose clip, d = 8…12 mm 40996.01 3

Digital thermometer 07050.00 1

Immersion probe NiCr-Ni 13615.03 1










Burette, 50 ml, with Schellbach line 36513.01 1





Pipettor 36592.00 1




Crystallisation dish, 1000 ml 46245.00 1


Erlenmeyer flask, 100 ml, narrow neck, SB 19 36418.00 2




What you need:



Ethyl acetate, 250 ml 30075.25 1

Hydrochloric acid, 1 M, 1000 ml 48454.70 1

Sodium hydroxide solution, 1 M, 1000 ml 48329.70 1

Phenolphthalein solution, 1%, 100 ml 31714.10 1


Reaction rate and activation energy of the acidhydrolysis of ethyl acetate P3050201

LEC_2 05.06.2008 18:32 Uhr Seite 65

66 Laboratory Experiments Chemistry

05.03 Kinetics of saccharose inversion

Principle and tasksThe inversion reaction of saccharose,which is catalysed by protons, pro-duces inverted sugar, a mixture ofglucose and fructose. This reaction isaccompanied by a change in the op-tical rotation of the system: Glucoserotates the polarisation plane oflinearly polarised light to the right,while inverted sugar rotates it to theleft.

Using a half-shade polarimeter, thechange in the angle of rotation ofpolarised light is measured, and therate constant of the inversion ofsaccharose is determined.

Floating point representation of saccharose inversion as a function of time.

Half-shade polarimeter 35906.93 1Immersion thermostat, 100°C 08492.93 1Accessory set for immersion thermostat 08492.01 1Bath for thermostat, 6 l, Makrolon 08487.02 1Rubber tubing, di = 6 mm 39282.00 2Hose clip, d = 8…12 mm 40996.01 3Magnetic heating stirrer 35720.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Magnetic stirrer bar, l = 30 mm 46299.02 1Support rod, l = 500 mm, M10 thread 02022.05 1Right angle clamp 37697.00 4Universal clamp 37715.00 3Universal clamp with joint 37716.00 1Stopwatch, digital, 1/100 s 03071.01 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Volumetric pipette, 10 ml 36578.00 7Pipettor 36592.00 1Pipette dish 36589.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Volumetric flask, 50 ml 36547.00 2Volumetric flask, 500 ml 36551.00 1Glass beaker, 100 ml, tall 36002.00 10Crystallisation dish, 1000 ml 46245.00 1Funnel, glass, do = 55 mm 34457.00 1Spoon 33398.00 1Wash bottle, 500 ml 33931.00 1D(+)-Saccharose, extra pure, 100 g 30210.10 1D(+)-Lactose, 100 g 31577.10 1Hydrochloric acid, for 1 l of 1 M standard solution, 1 ampoule 30271.00 1Water, distilled, 5 l 31246.81 1

What you need:

Kinetics of saccharose inversion P3050301



� Reaction rate� First order reaction� Polarimetry� Optical rotation

LEC_2 05.06.2008 18:32 Uhr Seite 66



Halogen exchange rate 05.07

Principle and tasksAlkyl halides experience rapid halo-gen exchange reactions in appropri-ate solvents. The velocity of thesesubstitution reactions occurs ac-cording to an SN2 mechanism. It canbe monitored via conductivity mea-surements if the number of chargecarriers changes in the course of thereaction.

The change of conductivity duringthe reaction of propyl bromide withsodium iodide (Finkelstein reaction)is measured. With the help of a cali-bration curve, the temporal concen-tration of sodium iodide can be de-termined. Based on the experimentaldata, the valid order of reaction isestablished and the rate constant isdetermined.

Concentration-time diagram for the Finkelstein reaction between propylbromide and iodide ions.

Conductivity meter 13701.93 1Conductivity / temperature electrode 13701.01 1Magnetic heating stirrer 35720.93 1Electronic temperature control 35721.00 1Magnetic stirrer bar, l = 25 mm 46300.01 1Magnetic stirrer bar, l = 50 mm 46299.03 1Stopwatch, digital, 1/100 s 03071.01 1Spring balance holder 03065.20 1Support rod with hole, l = 100 mm 02036.01 1Support rod, l = 750 mm, M10 thread 02023.20 1Right angle clamp 37697.00 3Universal clamp 37715.00 2Cristallizing dish, 1000 ml 46245.00 1Round flask, 100 ml, 2� GL 25/12, 1� GL 25/8 35677.15 1Condenser, Dimroth type GL 25/12 35815.15 1Glass tubes, straight, l = 80 mm 36701.65 1Rubber caps 02615.03 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Graduated cylinder, 100 ml 36629.00 1Syringe, 10 ml 02590.03 1Cannula, 0.6�60 mm 02599.04 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Powder funnel, do = 65 mm 34472.00 1Glass beaker, 50 ml, tall 36001.00 1

What you need:

Halogen exchange rateP3050701


� Reaction rate� First and second order reac-

tion laws� Conductometry

Spoon 33398.00 1Rubber tubing, d = 6 mm 39282.00 2Hose clips, d = 8...12 mm 40996.01 4N-propyl bromide, 250 ml 31756.25 1Sodium iodide, 50 g 31634.05 1Acetone, 250 ml 30004.25 1

LEC_2 05.06.2008 18:32 Uhr Seite 67

05.08 Conductometric measurements on the saponification of esters

Principle and tasksCarboxylic acid esters are saponifiedin an alkaline medium according to asecond order reaction rate. In theprocess, hydroxide ions with a highion mobility are consumed in reac-tion with an ester. The temporalcourse of reaction can be monitoredby using the measurements of thechanging conductance.

Change in the specific conductivity during the saponification of ethyl bu-tyrate in ethanol/water.

� Reaction rate� First and second order

reaction laws� Conductometry

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity / temperature electrode 13701.01 * 1Magnetic heating stirrer 35720.93 1Electronic temperature control 35721.00 1Magnetic stirrer bar, l = 25 mm, oval 46300.01 1Magnetic stirrer bar, l = 30 mm, cyclic 46299.02 1Support rod, l = 750 mm, M10 thread 02023.20 1Support rod with hole, l = 100 02036.01 1Spring balance holder 03065.20 1Right angle clamp 37697.00 3Universal clamp 37715.00 2Cristallizing dish, 1000 ml 46245.00 1Round flask, 100 ml, 2� GL 25/12, 1� GL 2/8 35677.15 1Condenser, Dimroth type GL 25/12 35815.15 1Glass tubes, straight, l = 80 mm 36701.65 1Rubber caps 02615.03 1Volumetric pipette, 25 ml 36580.00 2Pipettor 36592.00 1Syringe, 1 ml 02593.03 1Cannula, 0.6�60 mm 02599.04 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Wash bottle, 500 ml 33931.00 1Rubber tubing, di= 6 mm 39282.00 3Hose clamp d = 5...12 mm 40997.00 4Ethyl butyrate, 100 ml 48012.10 1Ethyl alcohol, absolute, 500 ml 30008.50 1Caustic soda solution, 0.1 M, 1000 ml 48328.70 1Standard solution, 1413 S/cm, 460 ml 47070.02 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:

Conductometric measurements on the saponification ofesters with Cobra3 Basic-Unit P3050811





Cobra3 Basic-Unit, USB 12150.50 1Measuring module, Conductivity 12108.00 1Software Cobra3 Conductivity 14508.61 1Thermocouple NiCr-Ni, sheated 13615.01 1Conductivity probe 18151.02 1

Conductometric measurements on the saponification ofesters with Cobra3 Chem-Unit P3050840

LEC_2 05.06.2008 18:32 Uhr Seite 68



Enzyme kinetics: Determination of the Michaelis constant 05.09

Principle and tasksIn the enzymatic hydrolysis of ureain aqueous solution, carbon dioxideand ammonia result. Their ions in-crease the conductivity of the solu-tion. The velocity of the urea hydrol-ysis by the enzyme urease is meas-ured via conductivity measurementsat different substrate concentrationsand the Michaelis-Menton constantis determined.

Conductivity-time diagram for the urea hydrolysis by urease.

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity probe 18151.02 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 1Universal clamp 37715.00 1Magnetic stirrer, mini 47334.93 1Magnetic stirring bar, l = 15 mm 46299.01 1Glass beaker, 100 ml, tall 36002.00 1Cristallizing dish, 320 ml 46243.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Erlenmeyer flask, 100 ml, narrow neck, SB 19 36418.00 6Rubber stoppers, d = 22/17 mm 39255.00 6Volumetric pipette, 20 ml 36579.00 1Pipettor 36592.00 1Microlitre syringe, 100 ml 02606.00 1Funnel, glass, do = 55 mm 34457.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Microspoon 33393.00 1Mortar with pestle, 70 ml 32603.00 1Wash bottle, 500 ml 33931.00 1Urea, 250 g 30086.25 1Urease solution in 50% glycerol, 10 ml 31924.03 1Standard solution, 1413 S/cm, 460 ml 47070.02 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:


� Michaelis-Mentonmechanism

� Reaction rate� Enzyme kinetics� Bodenstein principle� Electrolytic conductivity


Cobra3 Basic-Unit, USB 12150.50 1Measuring module, Conductivity 12108.00 1Software Cobra3 Conductivity 14508.61 1

Enzyme kinetics: Determination of the Michaelis constantwith Cobra3 Basic-Unit P3050911

Enzyme kinetics: Determination of the Michaelis constantwith Cobra3 Chem-Unit P3050940

LEC_2 05.06.2008 18:32 Uhr Seite 69

05.10 Enzyme kinetics: Inhibition and poisoning of enzymes

Principle and tasksIn the enzymatic hydrolysis of ureain an aqueous solution, carbon diox-ide and ammonia are produced; theirions increase the conductivity of thesolution. Via the conductivity meas-urements, the velocity of the hydrol-ysis of urea induced by the enzymeurease is measured at different sub-strate concentrations. By adding anappropriate inhibitor, the enzymecan be poisoned so that no furthersubstrate is converted.

Poisoning of the urease.

� Enzyme kinetics� Competitive, non-competitive

and uncompetitive enzymeinhibition

� Reversible and irreversibleenzyme inhibition

� Catalysis� Electrolytic conductivity

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity probe 18151.02 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 1Universal clamp 37715.00 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Glass beaker, 100 ml, tall 36002.00 1Cristallizing dish, 320 ml 46243.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Erlenmeyer flask, 100 ml, narrow neck, SB 19 36418.00 1Erlenmeyer flask, 250 ml, narrow neck, SB 29 36424.00 7Erlenmeyer flask, 500 ml, narrow neck, SB 29 36421.00 1Rubber stopper, d = 32/26 mm 39258.00 8Rubber stopper, d = 22/17 mm 39255.00 1Volumetric pipette, 50 ml 36581.00 7Volumetric pipette, 1 ml 36575.00 1Pipettor 36592.00 1Microlitre syringe, 100 �l 02606.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Microspoon 33393.00 1Mortar with pestle, 70 ml 32603.00 1Wash bottle, 500 ml 33931.00 1Urea, 250 g 30086.25 1Urease solution in 50% glycerol, 10 ml 31924.03 1Standard solution, 1413 S/cm, 460 ml 47070.02 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:




Enzyme kinetics: Inhibition and poisoning of enzymeswith Cobra3 Basic-Unit P3051011


Cobra3 Basic-Unit, USB 12150.50 1Measuring module, Conductivity 12108.00 1Software Cobra3 Conductivity 14508.61 1

Enzyme kinetics: Inhibition and poisoning of enzymeswith Cobra3 Chem-Unit P3051040

LEC_2 05.06.2008 18:32 Uhr Seite 70

Electro Chemistry6 Contents

LEC 06.01 Charge transport in solidsLEC 06.02 Charge transport in liquidsLEC 06.03 Ion migration velocityLEC 06.04 Transference numbersLEC 06.05 The temperature dependence of conductivityLEC 06.06 Conductivity of strong and weak electrolytesLEC 06.07 Conductiometric titrationLEC 06.08 Determination of the conductivity coefficientLEC 06.09 The Nernst equationLEC 06.10 Determination of the solubility products of the silver halidesLEC 06.11 Determination of diffusion potentialsLEC 06.12 Temperature dependence of the electromotive forceLEC 06.13 Potentiometric titrationLEC 06.14 Precipitation titrationLEC 06.15 pH measurementLEC 06.16 Titration curves and buffering capacityLEC 06.17 Potentiometric pH titration (phosphoric acid in a soft drink)LEC 06.18 Electrode kinetics: The hydrogen overpotential of metalsLEC 06.20 Amperometric equivalent point determ. with the dead stop methodLEC 06.21 Determination of Faraday’s constantLEC 06.22 Electrogravimetric determination of copper

LEC_2 05.06.2008 18:32 Uhr Seite 71


06.01 Charge transport in solids

Principle and tasksThe temperature coefficients of iron,copper and constantan wire are de-termined in the range of room tem-perature to 95°C. The temperaturedependence of the resistivity ofsolids provides information on themechanism of conduction andcharge transport in solids.

Dependence of resistance versus temperature (iron wire).



Software Cobra 3 Universal writer 14504.61 1

Current probe 6A 12126.00 1

Digital thermometer 07050.00 1

Immersion probe NiCr-Ni, Teflon 13615.05 1





Support rod, l = 250 mm 02031.00 1



Insulating pin 07807.00 2





Scissors, l = 180 mm, straight 64798.00 1

Copper wire, d = 0.2 mm, 100 m 06106.00 1

Iron wire, d = 0.2 mm, 100 m 06104.00 1

Constantan wire, d = 0.2 mm, 100 m 06100.00 1


What you need:

Charge transport in solidsP3060111

Electrochemistry LEC 06


� Electron conductivity� Ion conductivity

LEC_2 05.06.2008 18:32 Uhr Seite 72


Charge transport in liquids 06.02

LEC 06 Electrochemistry

Principle and tasksA potential difference between twoelectrodes in a liquid causes the flowof a current in the liquid. This currentdepends on the potential drop acrossthe liquid and its conductivity. Themeasurement of the conductivity ofelectrolyte solutions yields knowl-edge about charge transport in li-quids.

Conductivity of an aqueous potassium chloride solution at different temper-atures.

� Electrolyte solutions� Conductivity� Ionic migration

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity probe 18151.02 1Immersion probe NiCr-Ni, Teflon, 300°C 13615.05 * 1Magnetic heating stirrer 35750.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Support rod, l = 500 mm, M10 thread 02022.20 1Right angle clamp 37697.00 1Support for two electrodes 45284.01 1Spring balance holder 03065.20 1Burette clamp, roller mounting 37720.00 1Burette, 50 ml, lateral stopcock 36513.01 1Glass beaker, 250 ml, tall 36004.00 1Glass beaker, 150 ml, tall 36003.00 1Funnel, glass, do = 80 mm 34459.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Analytical balance CPA 224S (220 g/0.1 mg),set with software 49221.88 1Weighing dishes, 80�50�14 mm 45019.05 1Spoon 33398.00 1Cristallizing dish, 320 ml 46243.00 1Wash bottle, 500 ml 33931.00 1Glass rod, l = 200 mm, d = 5 mm 40485.03 1Desiccator 34126.00 1Porcelain plate for dessicators 32474.00 1Silicone grease, 100 g, 1 tube 31863.10 1Silica gel, orange, granulated, 500 g 30224.50 1Potassium chloride, 250 g 30098.25 1D (+) Sucrose, 100 g 30210.10 1Standard solution, 1413 S/cm, 460 ml 47070.02 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:

Charge transport in liquidswith Cobra3 Basic-Unit P3060211



Cobra 3 Basic-Unit, USB 12150.50 1Measuring module, Conductivity 12108.00 1Software Cobra3 Conductivity 14508.61 1Cobra3 sensor, -10…120°C 12120.00 1

Charge transport in liquidswith Cobra3 Chem-Unit P3060240

LEC_2 05.06.2008 18:32 Uhr Seite 73


06.03 Ion migration velocity

Principle and tasksThe movement of ions is responsiblefor current flow in electrolyte solu-tions. The migration of coloured ionscan be easily observed by the migra-tion of the colour front in an electricfield. In this experiment the migra-tion of the permanganate anion isdemonstrated and its ion velocity ismeasured at five different concen-trations.

Location of colour interface versus time.

Flat chamber for ionic migration 06605.00 1

Power supply, 0…600 V, regulated 13672.93 1

Multirange meter with amplifier 07034.00 1





Tripode base -PASS- 02002.55 1

Support rod, stainless steel, l = 500 mm 02031.00 1


Analytical balance CPA 224S (220 g/0.1 mg),set with software 49221.88 1







Funnel, glass, d0 = 55 mm 34457.00 2

Washbottle, 500 ml 33931.00 1

Potassium permanganate, 250 g 30108.25 1

Potassium nitrate, 250 g 30106.25 1


What you need:

Ion migration velocityP3060301



� Charge transport in liquids� Ion mobility� Conductivity

Ion mobility versus concentration.

LEC_2 05.06.2008 18:32 Uhr Seite 74


Transference numbers 06.04


Principle and tasksIn accordance with their different mo-bilities in an electric field, cations andanions contribute to charge transportin electrolytic processes. Hittorf trans-ference numbers are experimentallyaccessible via the resulting characte-ristic concentration changes occurringat the cathode and the anode. Thesecharacterise the proportion of a singletype of ion on the total charge trans-port through the given electrolytesand enable the calculation of ionicconductivities which are important inelectrochemical practice.

The Hittorf transference numbers ofthe oxonium and of the nitrate ion aredetermined for the electrolysis of a 0.1molar nitric acid solution.

� Electrolysis� Faraday’s laws� Charge transport� Ion mobility� Hittorf numbers


Multirange meter 07021.01 1


Connecting cord, l = 750 m, blue 07362.04 1


Double U-tube with frits and stopcock, GL25 44451.00 1

Contact socket for bar electrodes 45283.00 2

Carbon electrodes, d = 7 mm 44512.00 1

Plate electrodes, copper 07854.00 2

Holder for 2 electrodes 45284.01 1






Digital thermometer, NiCr-Ni 07050.00 1

Thermocouple, NiCr-Ni, sheated 13615.03 1


Microburette, 10 ml 36527.01 1









Pipettor 36592.00 1



What you need:



Funnel, glass, d0 = 55 mm 34457.00 1

Funnel, glass, d0 = 80 mm 34459.00 1

Spoon 33398.00 1


Washbottle, 500 ml 33931.00 1

Nitric acid, 1.0 M, 1000 ml 48448.70 1

Sulphuric acid, 0.05 M, 1000 ml 31831.70 1

Sodium hydroxide, 0.1 M, 1000 ml 48328.70 1

Copper (II) sulphate, 250 g 30126.25 1

Methyl red solution, 50 ml 30145.05 1

Acetone, 250 ml 30004.25 1


Transference numbersP3060401

LEC_2 05.06.2008 18:32 Uhr Seite 75


06.05 The temperature dependence of conductivity

Principle and tasksThe electrical conductivity of anelectrolytic solution depends notonly upon the type and concentra-tion of the electrolytes, but alsoother state values. Thus, an increasein conductivity is generally observedwith an increase in temperature. Thisis fundamentally due to the expo-nential decrease of the solutions’viscosity. In this experiment the tem-perature dependence of the conduc-tivity of a sodium chloride solution isdetermined in the range of 20°C to60°C.

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity probe 18151.02 1Immersion probe NiCr-Ni, Teflon, 300°C 13615.05 1Magnetic heating stirrer 35750.93 1Magnetic stirrer bar, l = 25 mm, oval 46300.01 1Electronic temperature control 35750.01 1Spring balance holder 03065.20 1Support rod, l = 750 mm, M10 thread 02023.20 1Support rod with hole, l = 100 mm 02036.01 1Right angle clamp 37697.00 2Universal clamp 37715.00 2Round flask, 100 ml, 2� GL 25/12, 1� GL 2/8 35677.15 1Condenser, Dimroth type GL 25/12 35815.15 1Cristallizing dish, 560 ml 46244.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Funnel, glass, do = 55 mm 34457.00 1Wash bottle, 500 ml 33931.00 1Glass beaker, 250 ml, tall 36004.00 1Glass rod, l = 300 mm, d = 8 mm 40485.06 1Spoon 33398.00 1Rubber tubing, di = 6 mm 39282.00 3Hose clamp d = 5...12 mm 40997.00 4Sodium chloride, 500 g 30155.50 1Standard solution, 1413 S/cm, 460 ml 47070.02 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:



� Electrolytic resistance� Specific and molar

conductivity� Ion mobility� Kohlrausch’s law� Ostwald’s law of dilution

Diagram of the conductivity as a function of the temperature.


Cobra 3 Basic-Unit, USB 12150.50 1Module converter 12150.04 1Data cable, RS232 14602.00 1

Measuring module, Conductivity 12108.00 1Measuring module, NiCr-Ni 12104.00 1Software Cobra3 Conductivity 14508.61 1

The temperature dependence of conductivitywith Cobra3 Basic-Unit P3060511

The temperature dependence of conductivitywith Cobra3 Chem-Unit P3060540

LEC_2 05.06.2008 18:32 Uhr Seite 76


Conductivity of strong and weak electrolytes 06.06


Principle and tasksIt is possible to differentiate betweenstrong and weak electrolytes bymeasuring their electrical conduc-tance. Strong electrolytes followKohlrausch’s law, whereas weakelectrolytes are described by Ost-wald’s dilution law. The examinationof the concentration dependence ofthe conductivity allows the molarconductivities of infinitely dilutedelectrolytes to be determined, andfacilitates the calculation of the de-gree of dissociation and the dissoci-ation constants of weak electrolytes.

Conductivity of a strong electrolyte as a function of the concentration.

� Kohlrausch’s law� Equivalent conductivity� Temperature-dependence of

conductivity� Ostwald’s dilution law

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity / temperature electrode 13701.01 * 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 1Spring balance holder 03065.20 1Support rod with hole, l = 100 mm 02036.01 1Glass beaker, 150 ml, tall 36003.00 2Volumetric flask, 250 ml 36550.00 4Volumetric flask, 500 ml 36551.00 4Volumetric flask, 1000 ml 36552.00 6Funnel, glass, do = 80 mm 34459.00 1Volumetric pipette, 1 ml 36575.00 2Volumetric pipette, 5 ml 36577.00 4Volumetric pipette, 25 ml 36580.00 4Volumetric pipette, 100 ml 36582.00 1Pipettor 36592.00 1Pipette dish 36589.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Analytical balance CPA 224S (220 g/0.1 mg),set with software 49221.88 1Weighing dishes, 80�50�14 mm 45019.05 1Spoon 33398.00 1Cristallizing dish, 320 ml 46243.00 1Wash bottle, 500 ml 33931.00 1Desiccator 34126.00 1Porcelain plate for desiccators 32474.00 1Silicone grease, 100 g, 1 tube 31863.10 1Silica gel, orange, granulated, 500 g 30224.50 1Acetic acid, 1 M, 1000 ml 48127.70 1Potassium chloride, 250 g 30098.25 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

What you need:

Conductivity of a weak electrolyte as a function of the concentration



Cobra3 Basic-Unit, USB 12150.50 1Measuring module, Conductivity 12108.00 1Software Cobra3 Conductivity 14508.61 1Conductivity probe 18151.02 1

Conductivity of strong and weak electrolyteswith Cobra3 Basic-Unit P3060611

Conductivity of strong and weak electrolyteswith Cobra3 Chem-Unit P3060640

LEC_2 05.06.2008 18:32 Uhr Seite 77


06.07 Conductiometric titration

Principle and tasksThe electric conductivity of aqueouselectrolyte solutions is determinedby the type and number of chargecarriers at constant temperature.Characteristic changes in conductiv-ity are connected with changes inthe ionic composition of reactingsystems. These can be used in theconductiometric titration as endpoint indicators. Using the Cobra3system, the change in conductivity inseveral titrations is measured.

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Conductivity / temperature electrode 13701.01 * 1Light barrier, compact 11207.20 1Connecting cord, l = 500 mm, red 07361.01 1Connecting cord, l = 500 mm, yellow 07361.02 1Connecting cord, l = 500 mm, blue 07361.04 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 2Universal clamp 37715.00 1Burette clamp, roller mounting 37720.00 1Burette, 25 ml 36506.01 1Glass beaker, short, 250 ml 36013.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Volumetric flask, 50 ml 36547.00 1Volumetric flask, 100 ml 36548.00 1Volumetric flask, 250 ml 36550.00 1Volumetric pipette, 5 ml 36577.00 3Volumetric pipette, 10 ml 36578.00 2Pipettor 36592.00 1Pipette dish 36589.00 1Funnel, glass, do = 55 mm 34457.00 1Funnel, glass, do = 80 mm 34459.00 1Spoon 33398.00 1Wash bottle, 500 ml 33931.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Sulphuric acid, 0.5 M, 1000 ml 48462.70 1Hydrochlorid acid, 0.1 M, 1000 ml 48452.70 1Acetic acid, 0.1 M, 1000 ml 48126.70 1Caustic soda solution, 0.1 M, 1000 ml 48328.70 1

What you need:



� Electrolytes� Specific conductance� Ion mobility� Ion conductivity� Conductometry

Titration diagram for the neutralisation of HCl solution with NaOH solution.

Barium hydroxide, 250 g 30034.25 1Standard solution, 1413 S/cm, 460 ml 47070.02 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher


Cobra3 Basic-Unit, USB 12150.50 1Measuring module, Conductivity 12108.00 1Measuring module, Temperature NiCr-Ni 12104.00 1Module converter 12150.04 1Data cable, RS232 14602.00 1Software Cobra3 Conductivity 14508.61 1Conductivity probe 18151.02 1Immersion probe NiCr-Ni, Teflon 13615.05 1

Conductiometric titrationwith Cobra3 Basic-Unit P3060711

Conductiometric titrationwith Cobra3 Chem-Unit P3060740

LEC_2 10.06.2008 14:55 Uhr Seite 78


Determination of the conductivity coefficient 06.08


Principle and tasksThe equivalent conductance ofstrong electrolytes depends on theirconcentration. The quotient of theequivalent conductance at a certainconcentration is the conductivity co-efficient. Like the activity coefficient,the conductivity coefficient is the re-sult of the interionic action.

The specific conductivities of dilutedpotassium chloride and calciumchloride solutions are determinedand the equivalent conductancesand conductivity coefficients arecalculated.

�c-�c-curves for potassium chloride and calcium chloride.

� Conductivity coefficient� Ion mobility� Equivalent conductance� Interionic action� Conductometry

Digital conductivity meter 13701.93 1

Conductivity / temperature electrode 13701.01 1

Protective sleeve for electrodes 37651.15 1





Support rod with hole, l = 100 mm 02036.01 1











Pipettor 36592.00 1



Desiccator, d = 150 mm 34126.00 1

Porcelain plate for desiccator 32474.00 1

Crystallizing dish, 320 ml 46243.00 1

Spoon 33398.00 1




Silica gel, orange, granular, 500 g 30224.50 1


What you need:

Determination of the conductivity coefficientP3060801


Standard solution, 1413 S/cm, 460 ml 47070.02 1

Potassium chloride, 250 g 30098.25 1

Calcium chloride, 250 g 48021.25 1


LEC_2 05.06.2008 18:32 Uhr Seite 79


06.09 The Nernst equation

Principle and tasksThe Nernst equation expresses howthe electrical potential of an electrodein contact with a solution of ions de-pends upon the activities of these ions.The equation may be experimentallyverified using an electrochemical cellformed from an inert indictator elec-trode coupled with a convenient refer-ence electrode. The potential of the in-dicator electrode, and hence the e.m.f.of the cell, are monitored as the ioniccomposition of the electrolyte solutionis changed.

Here a silver - silver chloride electrodeis used as reference electrode meas-uring the potential of a platinum elec-trode in contact with solutions con-taining different concentrations ofiron(II) and iron(III) complex ions.

Verification of the Nernst equation for the Fe(CN)64–, Fe(CN)63–� Pt redoxelectrode.

Digital pH-meter 13702.93 1Reference electrode, AgCl 18475.00 1Platinum electrode in protective tube 45206.00 1Connecting cord, l = 500 mm, black 07361.05 1Temperature probe Pt1000 13702.01 1Magnetic stirrer, Mini 47334.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Retort stand, h = 750 mm 37694.00 2Right angle clamp 37697.00 2Universal clamp 37715.00 1Support for two electrodes 45284.01 1Spring balance holder 03065.20 2Burette clamp, roller mounting 37720.00 1Burette, 50 ml, lateral stopcock 36517.01 2Analytical balance CPA 224S (220 g/0.1 mg),set with software 49221.88 1Weighing dishes, 80�50�14 mm 45019.05 1Glass beaker, 100 ml, tall 36002.00 2Glass beaker, 150 ml, tall 36003.00 4Volumetric flask, 1000 ml 36552.00 4Volumetric pipette, 50 ml 36581.00 2Pipettor 36592.00 1Pipette dish 36589.00 1Funnel, glass, do = 55 mm 34457.00 2Funnel, glass, do = 80 mm 34459.00 2Spoon 33398.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Wash bottle, 500 ml 33931.00 1Potassium hexacyanoferrate(II), 250 g 30101.25 1Potassium hexacyanoferrate(III), 100 g 30100.10 1Water, distilled, 5 l 31246.81 1

What you need:

The Nernst equation P3060901



� Electrode potentials and their concentrationdependence

� Redox electrodes� Electrochemical cells

LEC_2 05.06.2008 18:32 Uhr Seite 80


Determination of the solubility products of the silver halides 06.10


Principle and tasksA concentration cell is constructedfrom two half-cells which are identi-cal except that the concentration ofthe ionic species to which the elec-trode is sensitive is different in thetwo sides of the cell. Such a cell maybe used to measure the solubilityproduct of a sparingly soluble salt. Inone half-cell the concentration of oneof the ions is known, in the other it isgoverned by the solubility product ofthe salt. The ratio of the two concen-trations determines the e.m.f. of thecell.

Using a concentration cell made fromtwo silver - silver chloride electrodes,the solubility products of the threesilver halides AgCl, AgBr and AgI aredetermined.

� Concentration cells� Electromotive force� Salt bridge

Digital pH-meter 13702.93 1




Crocodile clips, bare 07274.03 1

Silver foil, 150�150�0.1 mm, 25 g 31839.04 1



Support for two electrodes 45284.01 1


Salt bridge 37684.00 1

Clay pins, d = 8 mm, l = 15 mm 32485.01 1



Syringe, 10 ml 02590.03 1

Cannula, 0.6�60 mm 02599.04 1








Graduated pipette, 5 ml 36598.00 1

Pipettor 36592.00 1




Spoon 33398.00 1


What you need:

Determination of the solubility productsof the silver halides P3061001



Glass rod, l = 200 mm, d = 5 mm 40485.03 1

Scissors, straight, l = 180 mm 64798.00 1


Nitric acid, 65%, 1000 ml 30213.70 1

Silver nitrate, 15 g 30222.00 1

Potassium nitrate, 250 g 30106.25 1

Potassium chloride, 250 g 30098.25 1

Potassium bromide, 100 g 30258.10 1

Potassium iodide, 50 g 30104.05 1


LEC_2 05.06.2008 18:32 Uhr Seite 81


06.11 Determination of diffusion potentials

Principle and tasksAt the interface between two solu-tions with different ion concentra-tions an electrochemical potentialestablishes itself. Its magnitude isdetermined by the concentrationratio and the transference numbersof the ions involved. This potentialdifference can be measured as afunction of the concentration atsemi-permeable and ion-selectivemembranes.

In this experiment we use a semi-permeable cellophane membraneand a cation-selective membrane tomeasure the diffusion gradients ofdifferent concentrations of HCl, NaCland KCl solutions.

Diffusion potential ��D for HCl as a function of In a2/a1 (0) and In c2/c1 (x)(for cellophane).

Osmosis / electrochemistry chamber 35821.00 1Gaskets for GL 25, 12 mm hole 41243.03 1Digital multimeter 07134.00 1Reference electrode, AgCl 18475.00 2Digital thermometer, NiCr-Ni 07050.00 1Thermocouple, NiCr-Ni, sheated 13615.03 1Stopwatch, digital, 1/100 s 03071.01 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 1Universal clamp 37715.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Volumetric flask, 100 ml 36548.00 6Volumetric flask, 1000 ml 36552.00 6Volumetric pipette, 1 ml 36575.00 2Volumetric pipette, 5 ml 36577.00 1Volumetric pipette, 10 ml 36578.00 1Volumetric pipette, 20 ml 36579.00 3Volumetric pipette, 50 ml 36581.00 3Pipettor 36592.00 1Pipette dish 36589.00 1Glass beaker, 100 ml, tall 36002.00 4Glass beaker, 250 ml, tall 36004.00 1Syringe, 1 ml 02593.03 1Cannula, 0.6�60 mm 02599.04 1Funnel, glass, do = 80 mm 34459.00 2Spoon 33398.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Scissors, straight, l = 110 mm, pointed 64623.00 1Wash bottle, 500 ml 33931.00 1Membrane, permeable for cations 31504.02 1Cellophane, 200�200 mm 32987.00 1Potassium chloride, 250 g 30098.25 1Sodium chloride, 500 g 30155.50 1Hydrochloric acid, 0.1 M, 1000 ml 48452.70 1Water, distilled, 5 l 31246.81 1

What you need:

Determination of diffusion potentials P3061101



� Nernst equation� Concentration cells� Transference numbers� Semi-permeable membrane� Selectively permeable

membrane

Diffusion potential ��D for KCl as a function of In c2/c1 (cation permeablemembrane).

LEC_2 05.06.2008 18:32 Uhr Seite 82


Temperature dependence of the electromotive force 06.12


Principle and tasksThe electromotive force is the poten-tial difference of the single poten-tials of the according electrodes in agalvanic chain. It is equal to the dif-ference of all the single potentialswhich can be calculated using theNernst equation. Thermodynamicdata of the gross reaction in a gal-vanic chain can be determined mea-suring the e.m.f. at different temper-atures.

The usable reaction equivalent workof the Daniell element is determinedby measuring the dependence of theelectromotive force on temperature.

Electromotive force versus temperature

� Electromotive force� Electrode reactions� Nernst equation� Electrochemical potential

Digital pH-meter 13702.93 1Copper electrode, d = 8 mm 45201.00 1Zinc electrode, d = 8 mm 45288.01 1Temperature meter, digital, 4-2 13617.93 1Temperature probe, Pt100 11759.01 3Protective sleeves for immersion probe 11762.05 1H-base -PASS- 02009.55 1Support rod, l = 250 mm 02031.00 1Support rod, l = 500 mm 02032.00 1Right angle clamp 37697.00 6Universal clamp 37715.00 2Universal clamp with joint 37716.00 2Holder for two electrodes 45284.01 1Immersion thermostat, 100°C 08492.93 1Accessory set for immersion thermostat 08492.01 1Bath for thermostat, 6 l, Makrolon 08487.02 1Rubber tubing, di = 6 mm 39282.00 4Hose clip, d = 8…12 mm 40996.01 4Two-way switch, double pole 06032.00 1Connecting cord, l = 500 mm, red 07361.01 1Connecting cord, l = 500 mm, blue 07361.04 1Connecting cord, l = 750 mm, red 07362.01 1Connecting cord, l = 750 mm, blue 07362.04 1Connecting cord, l = 100 mm, black 07359.05 1Holder for thermometer / tube 38002.01 1Salt bridge 37684.00 1Clay pins, d = 8 mm, l = 15 mm 32485.01 1Silicone tubing, di = 7 mm 39296.00 1Rubber caps 02615.03 1Syringe, 10 ml 02590.03 1Cannula, 0.6�60 mm 02599.04 1Glass beaker, 100 ml, tall 36002.00 3Glass beaker, 150 ml, tall 36003.00 4Glass beaker, 250 ml, tall 36004.00 2Volumetric flask, 250 ml 36550.00 3Graduated cylinder, 100 ml 36629.00 1Pasteur pipettes 36590.00 1

What you need:


Rubber bulbs 39275.03 1Funnel, glass, do = 55 mm 34457.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Spoon 33398.00 1Wash bottle, 500 ml 33931.00 1Nitric acid, 65%, 1000 ml 30213.70 1Copper(II) sulphate, 250 g 30126.25 1Zinc sulphate, 250 g 30249.25 1Potassium nitrate, 250 g 30106.25 1Water, distilled, 5 l 31246.81 1

Temperature dependence of the electromotiveforce P3061201

LEC_2 05.06.2008 18:33 Uhr Seite 83


06.13 Potentiometric titration

Principle and tasksIn a potentiometric titration theequivalence point is detected bymonitoring the electromotive force(e.m.f.) of an electrochemical cellformed by an indicator electrodecoupled with a convenient referenceelectrode. The potential of the indi-cator electrode, and hence the e.m.f.of the cell, is a measure of the activ-ity (approximately the concentra-tion) of the ionic species in the elec-trolyte solution. A potentiometrictitration on the iron(II)/cerium(IV)redox system with a 0.1 molariron(II) sulphate solution is per-formed to determine the concentra-tion of an unknown iron(II) solution.

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Adapter, BNC-plug/socket, 4mm 07542.26 * 1Reference electrode, AgCl 18475.00 1Platinum electrode 45206.00 1Connecting cord, l = 1000 mm, blue 07363.04 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 15 mm 46299.01 1Separator for magnetic bars 35680.03 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 1Holder for 2 electrodes 45284.01 1Spring balance holder 03065.20 2Burette clamp, roller mounting 37720.00 1Burette, 50 ml, lateral stopcock 36513.01 1Analytical balance CPA 224S (220 g/0.1 mg),set with software 49221.88 1Weighing dishes, 80�50�14 mm 45019.05 1Beaker, 1000 ml, short 36017.00 1Beaker, 250 ml, tall 36004.00 1Volumetric flask, 100 ml 36548.00 1Volumetric flask, 500 ml 36551.00 1Graduated pipette, 25 ml 36602.00 1Volumetric pipette, 10 ml 36578.00 1Pipettor 36592.00 1Graduated cylinder, 250 ml 36630.00 1Funnel, glass, do = 80 mm 34459.00 1Funnel, glass, do = 55 mm 34457.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Spoon 33398.00 1

What you need:



� Potentiometric titration� Redox reaction� Nernst equation� Quantitative analysis

Potentiometric redox titration curve for the Fe(II)/Ce(IV) system.

Wash bottle, 500 ml 33931.00 1Iron-II sulphate, 500 g 30072.50 1Cerium-IV disulphate, 25 g 31194.04 1Sulphuric acid, 95-98%, 500 ml 30219.50 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher


Cobra3 Basic-Unit, USB 12150.50 1Measuring module, pH/Potential 12101.00 1Software Cobra3 pH/Potential 14509.61 1

Potentiometric titrationwith Cobra3 Basic-Unit P3061311

Potentiometric titrationwith Cobra3 Chem-Unit P3061340

LEC_2 05.06.2008 18:33 Uhr Seite 84


Precipitation titration 06.14


Principle and tasksPrecipitation reactions which occurstoichiometrically and rapidly andwhose equilibrium lies on the side ofthe poorly soluble products can alsobe used titrimetrically. Consequently,a solution which contains both chlo-ride and iodide ions can be titratedwith a silver nitrate solution. Thecourse of the titration is monitoredpotentiometrically and the equiva-lence points are determined from theinflection points of the potentialcurve.

� Electrode potential� Cell voltage� Electrodes of the 1st and

2nd type� Nernst equation� Argentometry� Solubility product

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1Reference electrode, AgCl 18475.00 1Adapter, BNC-plug/socket, 4 mm 07542.26 * 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 30 mm, oval 46299.02 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 2Universal clamp 37715.00 2Burette clamp, roller mounting 37720.00 1Crocodile clip, insulated, black 07276.15 1Connecting cord, l = 500 mm, black 07361.05 1Burette, 50 ml, lateral stopcock 36513.01 1Glass beaker, 250 ml, tall 36004.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1

Weighing dishes, 80�50�14 mm 45019.05 1Volumetric flask, 100 ml 36548.00 3Volumetric pipette, 10 ml 36578.00 2Pipettor 36592.00 1Funnel, glass, do = 55 mm 34457.00 1Wash bottle, 500 ml 33931.00 1Microspoon 33393.00 1Scissors, l = 180 mm, straight 64798.00 1Silver foil, 25 g 31839.04 1Sodium chloride, 250 g 30155.25 1Sodium iodide, 50 g 31634.05 1

What you need:

Course of the potential during the precipitation titration.


Silver nitrate, crystalline, 15 g 30222.00 1Water, distilled, 5 l 31246.81 1PC, Windows 95® or higher

Changes in the equipment required for use of the Basic-Unit:(instead of * above mentioned)Cobra3 Basic-Unit, USB 12150.50 1Measuring module, pH/Potential 12101.00 1Software Cobra3 pH/Potential 14509.61 1

Precipitation titrationwith Cobra3 Basic-Unit P3061411

Precipitation titrationwith Cobra3 Chem-Unit P3061440

LEC_2 05.06.2008 18:33 Uhr Seite 85


06.15 pH measurement

Principle and tasksThe most important and commonmethod to determine the pH value isto measure the potential of an elec-trode which is sensitive to hydrogenion activity. Typically, an electro-chemical cell is constructed from apH sensitive electrode and a suitablereference electrode. The cell is thencalibrated by measuring its e.m.f. ina series of solutions of known pH.

A glass electrode, an antimony elec-trode and a quinhydrone electrodeare calibrated in buffer solutions andafter that used to measure the pH ofan unknown solution.

Calibration curves for the antimony (o) and quinhydrone (x) electrode. The celle.m.f. E is measured using a Ag(S)�AgCl(S)�Cl–(aq.) reference electrode.

Digital pH-meter 13702.93 1pH electrode, glass 18452.00 1Reference electrode, AgCl 18475.00 1Storage flask for pH-electrodes 18481.20 2Platinum electrode in protective tube 45206.00 1Antimony electrode 18477.00 1Temperature probe, Pt1000 13702.01 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Retort stand, h = 750 mm 37694.00 1Right angle clamp 37697.00 2Support for two electrodes 45284.01 1Spring balance holder 03065.20 2Universal clamp 37715.00 1Burette clamp, roller mounting 37720.00 1Connecting cord, l = 500 mm, black 07361.05 1Burette, 50 ml, lateral stopcock 36517.01 2Silver nitrate, crystalline, 15 g 30222.00 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Glass beaker, 150 ml, tall 36003.00 17Graduated cylinder, 100 ml 36629.00 1Volumetric flask, 1000 ml 36552.00 1Volumetric pipette, 10 ml 36578.00 2Volumetric pipette, 50 ml 36581.00 4Graduated pipette, 25 ml 36602.00 2Pipettor 36592.00 1Pipette dish 36590.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Funnel, glass, do = 55 mm 34457.00 2Funnel, glass, do = 80 mm 34459.00 1Spoon 33398.00 1Microspoon 33393.00 1Wash bottle, 500 ml 33931.00 1Quinhydrone, 100 g 31195.10 1

What you need:



� Potentiometric determinationof pH

� Glass electrode� pH indicators� Acid-base titrations

Methyl orange solution, 0.1%, 250 ml 31573.25 1Bromthymol blue, 1 g 31138.01 1Phenolphthalein solution, 1%, 100 ml 31714.10 1Citric acid, 250 g 30063.25 1Hydrochloric acid, 1 M, 1000 ml 48454.70 1Sodium hydroxide solution, 1 M, 1000 ml 48329.70 1Buffer solution, pH 4.62, 1000 ml 30280.70 1Buffer solution, pH 7.01, 1000 ml 46271.12 1Buffer solution, pH 9.00, 1000 ml 30289.70 1Ethyl alcohol, absolute, 500 ml 30008.50 1Water, distilled, 5 l 31246.81 1

pH measurement P3061501

LEC_2 05.06.2008 18:33 Uhr Seite 86


Titration curves and buffering capacity 06.16


Principle and taskspH values can be measured with theaid of electrochemical measure-ments and proton-sensitive elec-trodes (e.g. glass electrodes). Thetitration curves allow an exact de-termination of the equivalence pointin titrations of strong and weak acidsand bases.

Several strong and weak acids andbases as well as an ampholyte aretitrated and the buffering capacitiesof various buffer mixtures are deter-mined.

� Strong and weak electrolytes� Amphoteric electrolytes� Isoelectric point� Law of mass action� Buffering capacity� Henderson-Hasselbalch

equation

Cobra3 Chem-Unit 12153.00 * 1Power supply 12V/2A 12151.99 1Data cable, RS232 14602.00 1Software Cobra3 Chem-Unit 14520.61 * 1pH electrode, gel, BNC 46265.15 * 1Immersion probe NiCr-Ni, Teflon 13615.05 * 1Magnetic stirrer, mini 47334.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Retort stand, l = 750 mm 37694.00 1Burette clamp, roller mounting 37720.00 1Universal clamp 37715.00 1Right angle clamp 37697.00 1Burette 25 ml, lateral stopcock 36506.01 1Burette 50 ml, lateral stopcock 36513.01 2Volumetric flask 1000 ml 36552.00 4Volumetric flask 500 ml 36551.00 1Volumetric flask 250 ml 36550.00 7Graduated pipette, 1 ml 36595.00 1Graduated pipette, 10 ml 36600.00 1Volumetric pipette, 1 ml 36575.00 1Volumetric pipette, 2 ml 36576.00 1Volumetric pipette, 25 ml 36580.00 5Volumetric pipette, 50 ml 36581.00 5Pipettor 36592.00 1Pipette dish 36589.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Glass beaker, 250 ml, tall 36004.00 1Glass beaker, 150 ml, tall 36003.00 16Glass beaker, 100 ml, tall 36002.00 1Glass beaker, 50 ml, tall 36001.00 3Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Funnel, glass, do = 55 mm 34457.00 2Funnel, glass, do = 80 mm 34459.00 3Spoon 33398.00 1Wash bottle, 500 ml 33931.00 1Acetic acid, 1 M solution, 1000 ml 48127.70 1

What you need:

Titration curve of acetic acid with sodium hydroxide solution.


Caustic soda, 0.1 M solution, 1000 ml 48329.70 1Hydrochloric acid, 1.0 M, 1000 ml 48454.70 1Buffer solution, pH 4.62, 1000 ml 30280.70 1Buffer solution, pH 9.00, 1000 ml 30289.25 1Ortho-phosphoric acid 85%, 250 ml 30190.25 1Glycine, 100 g 31341.10 1Sodium acetate, 250 g 31612.25 1Water, distilled, 5 l 31246.81 1PC, Windows® 95 or higher

Changes in the equipment required for use of the Basic-Unit:(instead of * above mentioned)Cobra 3 Basic-Unit, USB 12150.50 1Measuring module, pH/Potential 12101.00 1Software Cobra3 pH/Potential 14509.61 1pH-Electrode, gel-filled 18450.00 1Measuring module, NiCr-Ni 12104.00 1Module converter 12150.04 1Data cable, RS232 14602.00 1

Titration curves and buffering capacitywith Cobra3 Basic-Unit P3061611

Titration curves and buffering capacitywith Cobra3 Chem-Unit P3061640

LEC_2 05.06.2008 18:33 Uhr Seite 87


06.17 Potentiometric pH titration (phosphoric acid in a soft drink)

Principle and tasksThe cell voltage and the Galvanivoltage of the electrodes of an gal-vanic cell are dependent upon theconcentration of the ions involved inthe potential forming process. Mea-suring the change of the cell voltagein the titrations of phosphoric acidand a beverage containing phospho-ric acid (E 338) conclusions can bemade about the beverage’s acid con-tent.

Titration curve of a beverage containing phosphoric acid.

Cobra3-Chem-Unit 12153.00 * 1


Data cable, RS232 14602.00 1

Software Cobra3 Chem-Unit 14520.61 * 1

pH-electrode, gel, BNC 46265.15 * 1

Immersion probe NiCr-Ni, Teflon 13615.05 1

Motor piston burette, 50 ml 36499.93 1

Cable Chem-Unit / Motor piston burette 36501.01 * 1

Rubber stopper, d = 18/14 mm, 1 hole 39254.01 1








Graduated pipette, 1 ml 36595.00 1


Pipettor 36592.00 1


Ortho-phosphoric acid, 85%, 250 ml 30190.25 1

Caustic soda solution, 0.1 M, 1000 ml 48328.70 1

Buffer solution, pH 4.62, 1000 ml 30280.70 1





What you need:



� Galvanic cell� Types of electrodes� Nernst equation� Potentiometry

Changes in the equipment required for use of the Basic-Unit:

(instead of * above mentioned)



Data cable, RS232 14602.00 1

Measuring module, pH/Potential 12101.00 1

Measuring module, NiCr-Ni 12104.00 1

Software Cobra3 pH/Potential 14509.61 1

Cable Basic-Unit / Motor piston burette 36501.03 1

pH-Electrode, gel-filled 18450.00 1

Potentiometric pH titration (phosphoric acid in a soft drink)with Cobra3 Basic-Unit P3061711

Potentiometric pH titration (phosphoric acid in a soft drink)with Cobra3 Chem-Unit P3061740

LEC_2 05.06.2008 18:33 Uhr Seite 88


Electrode kinetics: The hydrogen overpotential of metals 06.18


Principle and tasksElectrode polarization and the pres-ence of overpotentials are importantconcepts in understanding electrodeprocesses. They underlie the fact thatgalvanic cells always deliver current atless than the equilibrium e.m.f. and thatan applied potential greater than theequilibrium e.m.f. is required in order todrive a reaction in an electrolytic cell.

The current-potential curve for theelectrolysis of a 1 M hydrochloric acidsolution is recorded using graphite rodelectrodes, and the decompositionvoltage is determined. By replacing thegraphite rod cathode with a series ofdifferent metal rod electrodes, theoverpotentials for hydrogen evolutionat these metals can be compared.

Current-potential curve for the electrolysis of HCl solution using graphiteelectrodes.

� Electrode kinetics� Polarization� Overpotential� Voltammetry and current-

potential curves� Polarography



Software Cobra 3 Universal writer 14504.61 1

Current probe 6A 12126.00 1









Laboratory thermometer, –10... +50°C 38034.00 1

Carbon electrodes, d = 7 mm, l = 150 mm 44512.00 1

Copper electrode, d = 8 mm, l = 150 mm 45201.00 1

Iron electrode, d = 8 mm, l = 150 mm 45204.00 1

Lead electrode, d = 8 mm, l = 150 mm 45203.00 1

Nickel electrode, d = 8 mm, l = 150 mm 45205.00 1

Zinc electrode, d = 8 mm, l = 150 mm 45288.01 1


Hydrochloric acid, 1.0 M, 1000 ml 48454.70 1



Millimeter paper

Pencil

What you need:


Electrode kinetics:The hydrogen overpotential of metals P3061811

LEC_2 05.06.2008 18:33 Uhr Seite 89


06.20 Amperometric equivalent point determination with the dead stop method

Principle and tasksIn amperometric titration, the cur-rent intensity is measured as a func-tion of the added titrant. Here thecontent of an aqueous sodium thio-sulphate solution is determined bytitrating it with an iodine-potassiumiodide solution. The equivalencepoint can be determined ampero-metrically with platinum electrodes.

Course of the current in the titration of thiosulfate solution with iodine solu-tion.


Multirange meter with amplifier 07034.00 1


Rheostat, 100 �, 1.8 A 06114.02 1

Platinum electrode, protective tube, d = 8 mm 45206.00 2



















Pipettor 36592.00 1







What you need:

Amperometric equivalent point determination with the dead stop method P3062001



� Amperometric titration� Electrode polarisation� Maximum limiting diffusion

current� Overvoltage� Polarography


Sodium thiosulphate solution, 0.1 M, 1000 ml 48345.70 1

Iodine, 25 g 30093.04 1

Potassium iodide, 50 g 30104.05 1


LEC_2 05.06.2008 18:33 Uhr Seite 90


Determination of Faraday’s constant 06.21


Principle and tasksThe correlation between the amountsof substances transformed in theelectrode reaction and the appliedcharge is described by Faraday’slaws. Faraday’s constant, which ap-pears as a proportionality factor, canbe determined experimentally, in thiscase from the dependence of thevolumes of hydrogen and oxygenevolved on the applied charge in thehydrolysis of diluted sulphuric acid.

� Electrolysis� Coulometry� Faraday’s laws



Electrolysis apparatus after Hofmann 44518.00 1

Platinum electrode, protective sleeve, d = 8 mm 45206.00 2

On/Off switch 06034.01 1















Sulphuric acid, 95…98 %, 500 ml 30219.50 1


What you need:

Determination of Faraday’s constantP3062101


LEC_2 05.06.2008 18:33 Uhr Seite 91


06.22 Electrogravimetric determination of copper

Principle and tasksElectrogravimetry is an importantanalytical method for the quantita-tive determination or separation ofspecies in solution. The technique in-volves the quantitative electrolyticdeposition of an element, here copper,on a suitable electrode in a weigh-able form.

Power supply, universal 13500.93 1Digital multimeter 07134.00 2Platinum electrodes for electrogravimetry 45206.00 1Connecting cord, l = 500 mm, red 07361.01 1Connecting cord, l = 500 mm, blue 07361.04 1Connecting cord, l = 750 mm, red 07362.01 2Connecting cord, l = 750 mm, blue 07362.04 1Magnetic heating stirrer 35720.93 1Magnetic stirrer bar, l = 30 mm 46299.02 1Temperature sensor, electronic 35721.00 1Support rod, l = 500 mm, M10 thread 02022.20 1Spring balance holder 03065.20 1Support rod with hole, l = 100 mm 02036.01 1Holder for two electrodes 45284.01 1Right angle clamp 37697.00 2Analytical balance CPA 224S (220 g/0.1 mg),set with software 49221.88 1

Beaker, 250 ml, tall 36004.00 3Volumetric pipette, 50 ml 36581.00 1Graduated pipette, 10 ml 36600.00 1Pipettor 36592.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Wash bottle, 500 ml 33931.00 1Copper(II) sulphate, 0.1 M, 1000 ml 48247.70 1Sulphuric acid, 95…98 %, 500 ml 30219.50 1

What you need:

Electrogravimetric determination of copperP3062201



� Quantitative analysis� Electrolysis� Gravimetry� Overpotential and electrode

polarisation

Nitric acid, 65 %, 1000 ml 30213.70 1Ethyl alcohol, absolute, 500 ml 30008.50 1Water, distilled, 5 l 31246.81 1Drying oven

LEC_2 05.06.2008 18:33 Uhr Seite 92

Contents

LEC 07.01 Absorption of light

LEC 07.03 Excitation of molecules

LEC 07.04 Absorption spectra and pKa values of p-methoxyphenol

Photometry andPhotochemistry7

LEC_2 05.06.2008 18:33 Uhr Seite 93


07.01 Absorption of light

Principle and tasksIn dilute solution the solventchanges the binding relationships ofthe dissolved substance. This influ-ence shows itself in the electronspectrum.

An UV-VIS absorption spectra ofmethyl orange is recorded in differ-ent solvent. The type of electrontransition which causes the bands inthe visible region can be determinedvia the decadic molar extinction co-efficient.

Plot of the absorption maxima of methyl orange against the relative dielec-tric constants of different solvents.









Pipettor 36592.00 1

Microlitre syringe, 100 ml 02606.00 1



Methyl orange solution, 0.1 %, 100 ml 31573.10 1

Methyl alcohol, 500 ml 30142.50 1

Ethyl alcohol, 500 ml 30008.50 1

Ethylene glycol, 250 ml 30085.25 1

N,N-Dimethylformamide, 1000 ml 31259.70 1


What you need:

Absorption of lightP3070101

Photometry and Photochemistry LEC 07


� Electron excitation� Solvatochromism� Hypsochromic and

bathochromic shifts� Lambert-Beer law

LEC_2 05.06.2008 18:33 Uhr Seite 94


Excitation of molecules 07.03

LEC 07 Photometry and Photochemistry

Principle and tasksIn the spectral region between 200and 800 nm, which is recorded byUV-VIS spectroscopy, transitionsfrom the electronic ground state intoelectronically excited states occur.These transitions are induced by in-teraction of the investigated struc-tures with high-energy electromag-netic radiation.

The absorption of the polyenedyestuff carotene is recorded in thevisible region of the electromagneticspectra. The wavelength for the ab-sorption maximum is compared withthe value calculated according to themodel concept of the electron in aone-dimensional trough.

Absorption spectrum of carotene in acetone.

� Wave mechanical model ofthe atom

� Electron excitationspectroscopy

� Chemical colour theory� Lambert-Beer law






Suction filter, d = 70 mm 32707.00 2

Circular filter, d = 70 mm 32977.02 1

Filter flask, 250 ml 34418.01 1

Rubber gaskets, conical 39265.00 1


Petri dish, d = 150 mm 64757.00 1

PP stopper, IGJ 19/26 47506.00 1




Spoon 33398.00 1

Knife 33476.00 1

Thermometer, -10… +50°C 38034.00 1




Sea sand, purified, 1000 g 30220.67 1

Acetone, chemical pure, 250 ml 30004.25 1

Aluminium oxide S, acidic, 250 g 31084.25 1


Kitchen grater

Carrot

What you need:

Excitation of moleculesP3070301


LEC_2 05.06.2008 18:33 Uhr Seite 95


07.04 Absorption spectra and pKa values of p-methoxyphenol

Principle and tasksFor weak acids HA, the position of theKa and pKa values, which characterisethe dissociation equilibrium, can bedetermined in the ground state viaphotometric measurements in solu-tions having different pH values.Beyond this, the pKa* value for the ex-cited state is accessible from spectro-scopic data.

The absorption spectra from p-methoxyphenol in diluted HCl, NaOHand 5 different borate buffer solutionshaving known pH values are recordedin the near UV-region. From the mea-suring results, the pKa and pKa* valuesof the system can be calculated.

Absorption spectra of p-methyoxyphenol at different pH values.

Spectrophotometer 190 – 1100 nm 35655.93 1Cells for spectrophotometer 35664.02 1pH-potential meter, hand-held 07139.00 1pH-electrode, gel-filled, BNC 46265.15 1Protection sleeve for pH-electrodes 37651.15 1Precision balance CPA 623S (620 g/0.001 g), set with software 49224.88 1Weighing dishes, 80�50�14 mm 45019.05 1Retort stand, h = 750 mm 37694.00 1Burette clamp, roller mounting 37720.00 1Burette, 50 ml, with Schellbach line 36513.01 1Volumetric flask, 50 ml 36547.00 7Volumetric flask, 100 ml 36548.00 5Volumetric flask, 250 ml 36550.00 1Volumetric flask, 1000 ml 36552.00 1Volumetric pipette, 5 ml 36577.00 1Pipettor 36592.00 1Pasteur pipettes 36590.00 1Rubber bulbs 39275.03 1Funnel, glass, do = 55 mm 34457.00 2Microspoon 33393.00 1Laboratory thermometer, -10… +50°C 38034.00 1Wash bottle, 500 ml 33931.00 1Buffer solution pH 10.01, 1000 ml 46272.70 1Buffer solution pH 7.01, 1000 ml 46271.70 1p-Methoxyphenol, 5 g 31055.02 1Hydrochloric acid, 0.1 M, 1000 ml 48452.70 1Sodium hydroxide, 0.1 M, 1000 ml 48328.70 2Boric acid, powder, 250 g 30044.25 1Potassium chloride, 250 g 30098.25 1Water, distilled, 5 l 31246.81 1

What you need:

Absorption spectra and pKa values of p-methoxyphenolP3070401

Photometry and Photochemistry LEC 07


� Ground and excited states ofmolecules

� Jablonski diagram andFörster cycle

� Henderson-Hasselbalchequation

� Lambert-Beer law� Photometry

Graphic determination of the pKa value of p-methoxyphenol.

LEC_2 05.06.2008 18:33 Uhr Seite 96

Handbooks

84 described Experiments

Please ask for a completeequipment list Ref. No.25422

1. Mechanics1.1 (13301)Frequency of a spring pendulum1.2 (13302)Frequency of a thread pendulum1.3 (13369)Free fall with a screen1.4 (13370)The path-time law for free fallwith the falling sphere apparatus1.5 (13371)Uniform, linear, unacceleratedmotion1.6 (13372)Force-free, linear motion1.7 (13373)Uniformly accelerated, linear mo-tion, Newton`s 2nd law1.8 (13374)The elastic collision1.9 (13375)The inelastic collision1.10 (13376)Frequency of a thread pendulum1.11 (13377)Pendulum oscillations-variable g pendulum1.12 (13378)The harmonic oscillation of heli-cal springs-parallel and seriesconnection of spring1.13 (13379)Dependence of the oscillation pe-riod of a leaf spring on the pen-dulum length & pendulum mass1.14 (13380)Moment of inertia of differentbodies:disc,solid and hollowcylinder - Steiner`s law1.15 (13381)Uniform rotary motion1.16 (13382)Uniform, accelerated rotationalmotion, moment of inertia

2. Acoustics2.1 (13360)Measurement of frequency oftuning forks, detuning of tuningforks2.2 (13361)Investigation of the naturaloscillation of columns of air2.3 (13362)Measurement of the speed ofsound in air2.4 (13363)Measurement of the speed ofsound in diffent gases2.5 (13364)Measurement of the speed inmetal rods2.6 (13365)Acoustical Doppler effect2.7 (13615)Investigation of beats2.8 (13619)Influence of damping on thespectrum of the characteristicoscillations of air columns2.9 (13620)Characteristic oscillations in cavityresonators - Hemholtz's resonators2.10 (13621)Tone analysis

2.11 (13622)Oscillations in metal plates2.12 (13623)Speech analysis2.13 (13628)Signal filtration - elimination ofbackground noises2.14 (13629)Determination of the speed ofsound in air - travel time measure-ment between two microphones2.15 (13630)Acoustic spacial orientation

3. Thermodynamics3.1 (13491)Specific heat capacity of water3.2 (13492)Specific evaporation heat ofwater3.3 (13493)Specific heat capacity of liquids3.4 (13494)Specific heat capacity of solidbodies3.5 (13495)Specific condensation heat ofwater3.6 (13496)Specific melting heat of ice3.7 (13497)Specific dissolution heat of salts3.8 (13498)Specific heat value of fuels3.9 (13499)Volume expansion of gases3.10 (13500)Gay-Lussas Law3.11 (13501)Amontons Law3.12 (13502)Boyle's and Mariotte's Law3.13 (13641)Gay-Lussac's law3.14 (13642)Charles' (Amontons') law - variant A3.15 (13643)Charles' (Amontons') law - variant B3.16 (13644)Boyle and Mariotte's law

4 Electricity4.1 (13303)Ohm's Law4.2 (13304)Temperature dependence of theresistance of pure metals4.3 (13305)Characteristics of semi-conductordiodes4.4 (13306)Collector current-collector voltagecharacteristic of an NPN-transistor4.5 (13307)Second order conductors4.6 (13308)Switch-on current of aincandescent bulb4.7 (13309)Measurement of the work andpower of an incandescent bulb4.8 (13310)Switch-on behaviour of acapacitance4.9 (13311)Switch-on behaviour of aninductivity4.10 (13312)Induction impulse

61 described Experiments

Please ask for a complete equipmentlist Ref. No. 25423

1. Food Chemistry1.1 (13705)The manual titration of citric acid1.2 (13706)The automatic titration of ordinary vinegar1.3 (13707)Determination of the phosporic acid contentof a soft drink1.4 (13708)The pH and degree of acidity of coffee1.5 (13709)Determination of the content of fruit acidin juices and wine1.6 (13710)Titration curves of fresh milk and sour milk1.7 (13711)Changes in pH during the aging of milk(souring)1.8 (13712)The buffering properties of foods1.9 (13713)Determination of the calcium carbonatecontent of egg shell1.10 (13714)Determination of the common salt contentof meat broth1.11 (13715)Chloride in mineral water

2 Ecology and Environment2.1 (13701)The conductivity of various water samples2.2 (13702)The pH of various water samples2.3 (13703)The origin of acid rain2.4 (13704)The twenty-four hour rhythm of an aquaticplant2.5 (13509)Comparison of the heat capacities of waterand land2.6 (13510)The Bergman rule: heat loss in dependenceon body surface area and volume2.7 (13511)The isolating effect of body coverage2.8 (13325)Daily course of luminosity2.9 (13325)Daily course of luminosity

3. Biochemistry3.1 (13696)Determination of the isoelectric point of anamino acid (glycine)3.2 (13697)The ionic permeability of the cell membrane3.3 (13698)Determination of the Michaelis constant3.4 (13699)Substrate inhibition of enzymes3.5 (13700)Enzyme inhibition (poisoning of enzymes

4. Nerves Physiology4.1 (13600)Neuro-simulator (membrane time constantand low-pass filtering)4.2 (13601)Neuro-simulator (how an exciting synapsefunctions)4.3 (13602)Mechanical stimulation of the rear end ofan earthworm4.4 (13603)Mechanical stimulation of the front end ofan earthworm4.5 (13604)Electrical stimulation of an anaesthesizedearthworm

5. Human Physiology5.1 (13326)Cardiac and vasular sonic measurement(Phonocardiography)5.2 (13327)Electrocardiography5.3 (13327)Electrocardiography5.4 (13503)Electromyography5.5 (13605)Muscle stretch reflex and determination ofconducting velocity5.6 (13504)Electro-oculography5.7 (13326)Cardiac and vascular sonic measurement(Phonocardiography)5.8 (13606)Acoustic orientation in space5.9 (13607)The enzymatic activity of catalase5.10 (13505)Blood pressure measurement5.11 (13506)Measurement of the respiratory rate5.12 (13507)Changes in the blood flow during smoking5.13 (13508)Regulation of body temperature

6. Plant Physiology6.1 (13608)Photosynthesis (bubble-counting method)6.2 (13513)Photosynthesis (measurement of oxygenpressure)6.3 (13512)Transpiration of leaves6.4 (13609)Glycolysis (measurement of pressure)6.5 (13514)Glycolysis (measurement of temperature6.6 (13515)Calorimetry of foods

7. Electrochemistry7.1 (13318)Electrolysis of copper sulphate solutions7.2 (13319)The electrochemical series of metals7.3 (13320)Electric potential of a concentrationelement

8. Chemical equilibrium8.1 (13321)Chromatographic seperation processes: gas chromatography

9. Gas laws9.1 (13499)Volume expansion of gases (with Software Pressure)9.2 (13500)Gay-Lussas Law (with Software Pressure)9.3 (13501)Amontons Law (with Software Pressure)9.4 (13502)Boyle's and Mariotte's Law (with Software Pressure)9.5 (13641)Gay-Lussac's law (with Software Gas Laws)9.6 (13642)Charles' (Amontons') law - variant A (with Software Gas Laws)9.7 (13643)Charles' (Amontons') law - variant B (with Software Gas Laws)9.8 (13644)Boyle and Mariotte's law (with Software Gas Laws)

Computer assisted Experiments with Cobra3 Physics, Chemistry /Biology

Cobra3 Physics • No. 01310.02

Cobra3 Chemistry/Biology • No. 01320.02

4.11 (13313)Generation of an alternating cur-rent, rectification and filtration4.12 (13314)Efficiency of motor and generator4.13 (13366)Measurement of the reboundtime of a switch4.14 (13367)Current-voltage characteristic ofa solar cell4.15 (13611)Single-valued and multiple-valued Fourier spectra4.16 (13612)Analysis of simple and compositesinusoidal signals4.17 (13613)Spectral analysis of differentsignal forms - sinusoidal, rectan-gular, triangular signals4.18 (13614)Spectral analysis of periodic spikepulses4.19 (13616)Determination of the non-lineardistortion factor from the Fourierspectrum of distorted sinusoidaloscillations4.20 (13617)The Fourier spectrum of rectified,non-smoothed alternating currents4.21 (13618)Investigation of the characteristicoscillations of air columns4.22 (13624)Coupled electrical resonant cir-cuits4.23 (13625)Forced oscillations of a non-linearelectrical series resonance circuit- chaotic oscillation4.24 (13626)Analysis of Fourier series4.25 (13627)High-pass, low-pass, bandpassfilters4.26 (13631)Switch rebound4.27 (13632)Phase relationships in a seriesresonant circuit4.28 (13633)Free damped oscillation

5. Optics5.1 (13315)Dependence of the luminousintensity on the distance

6. Physical Structure of Matter6.1 (13368)Franck-Hertz Experiment6.2 (13634)Range of alpha particles in the air6.3 (13635)Mean range of beta radiation in air6.4 (13636)Absorption of electrons (orpositrons) in thin layers of matter6.5 (13637)The quantal flux of gammaradiation in air6.6 (13638)Absorption of gamma quanta (or electrons) as a function ofmaterial density6.7 (13639)Law of radioactive decay6.8 (13640)Radioactive equilibrium


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98

AActivation energy 65

Adiabatic coefficient of gases 23

Adsorption 62

Amontons’ law 18

Amperometric titration 90

Avogadro’s law 51

BBoiling point 31, 42

Boyle and Mariotte’s law 19

Bubble pressure method 56

Buffering capacity 87

CCalorific value 36

Calorimetry 25, 27, 28, 2930, 34, 35, 36

Capillary viscometer 13

Charge transport 72, 73, 74, 75

Clausius-Clapeyron equation 40

Complex formation 48

Conductometry 67, 68, 6970, 77, 78, 79

Contact angle 59

Coulometry 91

Critical point 22

Cryoscopy 32

DDiffusion coeffiecient 10

Diffusion potential 82

Dilatometry 37

Dissociation 46, 47, 49

Distillation 52, 53

Distribution 45

Du Nouy method 57

EEbullioscopy 31

Electrochemical cells 80, 85, 86

Electrogravimetry 92

Electrokinetic potential 60

Electrolysis 91, 92

Electrolysis apparatusafter Hofmann 91

Electrolyte conductivity 58

Electrolytes 74, 75, 76, 7778, 79, 87

Electromotive force 81, 83, 84

Electron conductivity 72

Electron excitation 94, 95

Electrophoresis 61

Enthalpy of combustion 33, 36

Enthalpy of formation 33, 34, 35

Enthalpy of neutralisation 29

Enthalpy of vaporization 25, 40

Enzyme inhibition 70

Enzyme kinetics 69, 70

Equations of stateof ideal gases 11, 12

Eutectic mixture 50

Evaporative equilibrium 40

FFalling ball viscometer 15

Faraday’s law 91

Fick’s laws of diffusion 10

Flammersfeld oscillator 23

Freezing point depression 32

GGas chromatography 14, 53, 54

Gay-Lussac’s law 17, 51

General equation of state 17, 1819, 51

Gibb’s phase law 44, 50

Gravimetry 92

HHeat capacity 24, 25, 27, 28

29, 30, 33, 36

Heat of formation 34, 35

Henderson-Hasselbalch 47,4987, 96

Hess’ law 28, 33, 35

Hittorf transference numbers 75

Hydration enthalpy 28

IIon conductivity 73, 78

Ion mobility 46, 74, 7576, 78, 79

Ionic conductivity 46

KKohlrausch’s law 77

LLambert-Beer law 45, 49, 94

95, 96

Law of integral ratioof volumes 51

Law of mass actio 87

MMAXWELL BOLTZMANN 8

Melting enthalpy 30

Melting point 50

Michaelis-Menton mechanism 69

Miscibility gap 43, 44

Mixing enthalpy 27

Mixtures 41, 42, 43, 44

Molar mass 11, 12

Molecular weight 1

NNernst equation 80, 82, 83

84, 85, 87

Nernst’s distribution law 45

Newtonian liquid 15, 16

non-Newtonian liquid 16

OOptical rotation 66

Ostwald’s dilution law 77

Overpotential 89, 92

PPartial molar volumes 26

pH indicators 86

pH titration 86, 87

pH value 86, 87, 88, 95

pKa value 47, 49, 96

Poiseuille’s formula 9

Poiseuilles’s equation 13

Polarization 89

Potentiometric titration 84, 88

Precipitation titration 85

Proteins 61

RRaoult’s law 31, 32, 41, 42

Rate law 64, 65

Reaction law 67

Reaction order 64, 67, 68

Reaction rate 65, 67, 68, 69

Rectification 52, 53

Rotary viscometer 16

SSaccharose inversion 66

Saponification rate 64

Solubility 43, 46

Solubility product 81, 85

Solvatochromism 94

Stokes law 15

Surface tension 56, 57, 58, 59

TTensides 58

Theoretical trays 52, 54

Thermal conductivity 14

Thermal equation 22

Thermal expansion 37

Trouton’s rule 25

VVapour pressure 40, 41

Vapour-density method 12

Velocity distribution 8

Victor Meyer 12

Viscosity 9, 13, 15, 16

Volume contraction 26

Index

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99

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