thermo manual

8/6/2019 Thermo Manual

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LISTS of EXPERIMENTS

DEW POINT HYGROMETER

Experiment # 1: To determine the dew point, absolute

humidity & relative humidity with the help of dew point hygrometer.

BOYLES LAW APPARATUS

Experiment # 2: To verify that when the volume of an ideal

gas (Air) is changed at constant temperature, the product of its

pressure and volume remains constant (Boyles Law)

MECHANICAL EQUIVALENT OF HEAT APPARATUS

Experiment # 3: To determine the Mechanical Equivalent of

heat

Experiment # 4: To determine the specific thermal capacity

of given solid bodies by using mechanical equivalent of heat

apparatus.

DILATOMETER

Experiment # 5: To determine the linear expansion of brass,

iron, copper, aluminum, Duran glass and quartz glass as a function

of temperature (five different temperatures ranging between 20C

and 70C) using a dilatometer. Calculate the linear expansion

coefficients.


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Experiment # 6: To determine the thermal expansion of

water as a function of temperature (five different temperatures

ranging between 20C and 70C.), using the pycnometer

MOLAR MASS APPARATUS

Experiment # 7: Determine the molar masses of liquid.

Discuss the results in terms of the real and ideal behavior of vapors.

Experiment # 8: Determine the molar masses of gases.

Discuss the results in terms of the real and ideal behavior of gases

CRITICAL POINT APPARATUS

Experiment # 9: Determine the critical point of a substance

CALORIMETERY

Experiment # 10: Determine the enthalpy of vaporization of

pure liquid

Experiment # 11: Determine the enthalpy of mixing of mixture


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LISTS of EXPERIMENTS

Experiment # 1: To determine the dew point, absolute

humidity & relative humidity with the help of dew point hygrometer.

Experiment # 2: To verify that when the volume of an ideal

gas (Air) is changed at constant temperature, the product of its

pressure and volume remains constant (Boyles Law)

Experiment # 3: To determine the Mechanical Equivalent of

heat

Experiment # 4: To determine the specific thermal capacity

of given solid bodies by using mechanical equivalent of heat

apparatus.

Experiment # 5: To determine the linear expansion of brass,

iron, copper, aluminum, Duran glass and quartz glass as a function

of temperature (five different temperatures ranging between 20C

and 70C) using a dilatometer. Calculate the linear expansion

coefficients.

Experiment # 6: To determine the thermal expansion of

water as a function of temperature (five different temperatures

ranging between 20C and 70C.), using the pycnometer

Experiment # 7: Determine the molar masses of liquid.

Discuss the results in terms of the real and ideal behavior of vapors.

Experiment # 8: Determine the molar masses of gases.

Discuss the results in terms of the real and ideal behavior of gases

Experiment # 9: Determine the critical point of a substance


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Experiment # 10: Determine the enthalpy of vaporization of

pure liquid

Experiment # 11: Determine the enthalpy of mixing of mixture


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EXPERIMENT # 1DEW POINT HYGROMETER

OBJECTIVE:

To determine the dew point, absolute humidity & relative humidity

with the help of dew point hygrometer.

APPARATUS:

Dew point apparatus, Thermometer, Right angled glass tube, obtuse

angled glass tube, three stopper and Rubber bulb for pumping air.

CHEMICALS REQUIRED:

n-pentane or any low Boiling point liquid.

Assembly:

Dew point fills the metal tube to about two third with n-pentane and

fit on the stopper. Thermometer and Right angled glass tube should

be so positioned in stopper that their bottom ends reach down to

just above the bottom of the tube. While obtuse angled glass tube

which acts as outlet for vapor evolved, ends just below the bottom

of Rubber stopper.

PROCEDURE:

Pump air through the surface of pentane slowly and continuously by

using the rubber bulb. Observe the outer surface of tube and the

comparison mirror while pumping air. A misting up of the tube

surface as compared to the mirror will be recognized while pumping

air through pentane.


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Record this temperature as T1. Stop blowing air through pentane

and wait until misting disappear and record the corresponding

temperature as T2.


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OBSERVATIONS & CALCULATIONS

Temperature when Mist appear = T1 = ______________

Temperature when Mist disappear =T2 = ____________

1. Dew Point

The dew point temperature is the average of T1 & T2.

2. Absolute Humidity

Water vapor density at dew point Temperature = s

=__________ kg/m3

3. Relative Humidity

Room temperature = T =_____________

Saturated Water vapor density at room Temperature =

=__________kg/m3

Relative humidity of atmosphere can be calculated as

Where;

= Relative humidity

s = Saturated Water vapor Density i.e. Density of water

vapor at dew point

= Saturated Water vapor Density at Room Temperature.

ASSIGNMENT:


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What are different types of hygrometers used in industry

and for what applications? State at least five types along

with their working principles.


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EXPERIMENT # 2BOYLES LAW

OBJECTIVE:

To verify that when the volume of an ideal gas (Air) is changed at

constant temperature, the product of its pressure and volume

remains constant (Boyles Law)

APPARATUS:

Boyles Law apparatus, water having pressure of around 4 bars.

BOYLES LAW APPARATUS:

Boyles Law apparatus consists of a glass cylinder of 50 cm length

and 5 cm diameter. The glass cylinder is graduated having 10

graduations; the fractional parts , 1/3, , 2/3, & of the total,

volume are also marked. The cylinder is enclosed in a transparent

plastic tube for protection. A safety valve is also installed that

responds when an air pressure approx. 4.5 bars are reached.

Pressure associated to the volume of air in cylinder is indicated by a

manometer connected to the apparatus. The manometer ranges

from 0 to 4 bars. Tap water to compress/expand the enclosed

volume of air is introduced into/Drained from the cylinder as

required by means of two taps having pressure tubing of 1.5 meter

length.

PROCEDURE:

The volume of air under investigation is contained in a glass cylinder

which is closed at the top. To remove all the air from supply tube,

the tube must be completely filled with water. Water is introduced


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at the base of the cylinder by means of pressure tube. Water rises

and compresses the enclosed volume of air in the glass cylinder.

The volume of compressed air, relative to its initial volume at

atmospheric pressure, is measured on the cylinder scale. The

associated pressure is read off from manometer and tabulated.

OBSERVATIONS & CALCULATIONS: -

Total volume of cylinder = ________________ ml

Volume of one graduation of cylinder = _____________ ml

Sr.No.

Volumeoccupiedby H2O

Volume ofoccupiedby air

Pressurecorresponding tovolume of air

PV

(ml) (ml) (bar)

12345

NOTE:-

This law can also be observed by increasing the volume of air step

wise and readings will be tabulated in the same table.

RESULT:-

Discus your Result

PRECAUTIONS:-

The inflow tube must be completely filled with water in order

to remove all the air.

Water is allowed to flow slowly into the cylinder to compress

the air.

The measuring range of manometer should not be exceeded.


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The water should run out of the cylinder at the completion of

experiment.

ASSIGNMENT:


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EXPERIMENT #3MECHANICAL EQUAVALENT OF HEAT

OBJECTIVE:

To determine the Mechanical Equivalent of heat

APPARATUS

Mechanical equivalent of heat apparatus, spring balance, weight,

thermometer and friction cylinders.

PROCEDURE

Determine the mass of Friction cylinder by weighing it and Fix

the Friction Cylinder and crane handle to the journal bearing.

Hang a spring balance from the holder.

Attach the friction band to the spring balance.

Wrap the band 2.5 times around the cylinder so that the load

on the balance is relieved if crank handles is turned to right.

Attach a weight to the lower end of the friction band.

Fill the hole in the cylinder with the thermally conducting

paste and measure the temperature of cylinder at start of

experiment (T1)

Make a definite number of rotations (say 100) with the crank

handle as evenly as possible. Spring balance then indicate a

constant force F1.

Note the temperature T2, after definite rotations.


13/34


Mass of Friction Cylinder = m = ____________ kg

Radius of Friction Cylinder = r = ____________ cm

Force due to mass of friction cylinder =F1= mg = _______________ N

Initial Temperature of Cylinder = T1 = _______________C + 273.15 =

________________ K

Thermal heat capacity of heated parts = Ctotal = Ccylinder + Cband +

Cthermometer=____________ J/K

Sr.No

Numberof

rotationsn

ForceonSpring

Balan

ceF2(N)

CylinderTemperatur

eatendT2(K)

Workduetofriction

W=2rn(F2F

1)(N

)

Thermal

EnergyQ

=Ctotal

(T2

T1)( J)

12

345

From literature thermal heat capacity for;

Cu Zn material, specific = c=Ccylinder/m = 0.385 J/gK

Friction band = Cband = 4 J/K

Thermometer = Cthermometer = 4 J/K

RESULT


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Discus your Result


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EXPERIMENT # 4MECHANICAL EQUAVALENT OF HEAT

OBJECTIVE:

To determine the specific thermal capacity of given solid bodies by

using mechanical equivalent of heat apparatus.

APPARATUS

Mechanical equivalent of heat apparatus, spring balance, weight,

thermometer and friction cylinders.

PROCEDURE

Determine the mass of Friction cylinder by weighing it and Fix

the Friction Cylinder and crane handle to the journal bearing.

Hang a spring balance from the holder.

Attach the friction band to the spring balance.

Wrap the band 2.5 times around the cylinder so that the load

on the balance is relieved if crank handles is turned to right.

Attach a weight to the lower end of the friction band.

Fill the hole in the cylinder with the thermally conducting

paste and measure the temperature of cylinder at start of

experiment (T1)

Make a definite number of rotations (say 100) with the crank

handle as evenly as possible. Spring balance then indicate a

constant force F1.

Note the temperature T2, after definite rotations.

Change the friction cylinder and repeat the same procedure


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Number of rotations = n = ____________

Initial Temperature of Cylinder = T1 = _______________C


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Mater

ialofFrictionCylin

der

Mass

ofFrictionCylinderm

Radiu

sofFrictionCylinde

rR

Force

duetomassoffrict

ioncylinde

rF

1

=mg

Force

onSpringBalanceF

2

Cylin

derTemperatureaten

dT

2

Work

duetofrictionW

=2

rn

(F

2

F

1

)

Tempe

raturedifferenceT=

T

2

T

1

(k

g)

(c

m

)

(

N

)

(

N

)

(K

)

(

N

)

(K

)

(J/K) (J/g-K)

Z


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n

-

C

uA

l

u

m

i

n

u

mB

r

a

s

s

RESULT

Discus your Result and compare them with literature value


19/34

EXPERIMENT # 5DILATOMETER

OBJECTIVE:

To determine the linear expansion of brass, iron, copper, aluminium,

duran glass and quartz glass as a function of temperature (five

different temperatures ranging between 20C and 70C) using a

dilatometer. Calculate the linear expansion coefficients.

ASSEMBLY :

Set up the experiment as shown in following Figure.

PROCEDURE:

Clamp the first tube over its whole length (600 mm) in the

dilatometer and connect it to the circulating pump of the thermostat

via rubber tubing. Keep the tubing as far as possible away from the

dilatometer in order not to heat up the frame of the dilatometer. For

the same reason, avoid long periods of readjustment of the

temperature controlled bath and set the temperature only with the

accuracy of the thermostatic control. After the initial temperature

(approximately 20C) has been reached, set the meter to 0, and

then raise the temperature in four steps, each of 10C to 15C.

Record the respective changes in length and the corresponding

temperatures.

Repeat this measurement series with each of the remaining four

materials.


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Room Temperature = T1 = _______________C

RESULT

Discus your Result and compare them with literature

value


21/34

EXPERIMENT # 6THERMAL EXPANSION

OBJECTIVE:

To determine the thermal expansion of water as a function of

temperature (five different temperatures ranging between 20C

and 70C.), using the pycnometer

PROCEDURE:

The volume of the pycnometer is determined and the scale

calibrated by weighing it empty and then filled with destilled water.

The pycnometer, filled with the liquid to be measured, is brought to

temperature in the water bath (thermostat). The change in volume

is read from the scale on the tube built into its stopper.

Measure the water volume at five different temperatures between

20C and 70C. In a fluid, a temperature increase intensifies the

thermal movement of the particles and hence increases the volume.


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23/34

EXPERIMENT # 7MOLAR MASS OF LIQUID

OBJECTIVE:

Determine the molar masses of liquid. Discuss the results in terms

of the real and ideal behavior of vapors.

Procedure:

Switch on the heating apparatus and adjust the power regulator so

that the water is brought to gentle boiling. When the water has

reached a constant temperature, perform the measurements as

follows: Draw a small quantity of the liquid to be investigated (e.g.

approx. 0.12 ml of methanol or approx. 0.3 ml of diethyl ether) into

the injection syringe without bubbles. Clean the cannula externally

with a paper towel and determine the total weight of the syringe

with cannula and substance to an accuracy of 1 mg. Record the

exact volume of air contained in the gas syringe. Now rapidly inject

the substance through the rubber cap. Ensure that the whole test

substance has been injected into the cylinder of the gas syringe and

nothing has remained in the capillary tube. Let the injection syringe

stuck in the rubber cap until the vapour volume no longer changes.

Ensure that pressure equilibrium between the syringe and the

atmosphere has been reached by turning the cylinder of the glass

syringe slightly, then read off the volume of the vaporized liquid.

Reweigh the empty syringe and calculate the mass of the

substance. Perform three measurements for each of the two liquids

in this manner. After each measurement, remove the rubber cap


24/34

from the gas syringe and rinse the syringe with air by pushing the

plunger backwards and forwards several times.


25/34

OBSERVATIONS & CALCULATIONS:

Liquid used in experiment = ________________

Mass of empty syringe = m = ______________ g

Atmospheric Pressure = P = ________________ kPa

Sr#

Temperature

Volumefilledin

syringe

Massofliquidi

nsyr

ingem

Volumeofvaporize

dliquidV

C

(ml)

(g) (ml)

(g/gmol) (g/gmol)

Where;

a,b = Van der waals constant

Results

Discus your Result and compare them with each other and literature

value


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EXPERIMENT # 8MOLAR MASS OF GAS

OBJECTIVE:

Determine the molar masses of gases. Discuss the results in terms

of the real and ideal behavior of gases.

PROCEDURE:

Thoroughly clean and dry the syringe and the glass bulb and lightly

grease the three-way stopcock (do not grease the syringe plunger!).

Assemble the apparatus as shown in Fig. 1. Make sure that the

plunger stop is positioned to prevent the plunger from being fully

removed from the syringe barrel whilst still allowing the syringe to

be filled to its maximum volume of 100 ml. In the following, S1 is the

three-way stopcock on the gas syringe, S2 is the Teflon stopcock

between S1 and the glass bulb and S3 is the Teflon stopcock

between the glass bulb and the pump

To determine the mass of the glass bulb, close S2, open S3 and

evacuate the glass bulb by pumping for 10 minutes, close S3,

disconnect the bulb from the vacuum line and weigh it. Following

this, reconnect the bulb to the vacuum line and open S2 and S3.

Turn S1 to connect both the syringe and the bulb to the gas bottle

and evacuate the entire vacuum line for a further 5-10 minutes.

Close S2 and S3 and carefully open the needle valve regulator on

the gas bottle to fill the syringe with gas. Record the volume of gas

introduced into the syringe (between 95 and 100 ml) to the nearest

0.5 ml. Fill the bulb with gas by turning S1 through 180 and slowly


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open S2. After closing S2, remove the bulb from the vacuum line

and re-weigh it. Calculate the mass of the gas in the bulb and record

it together with the ambient pressure and temperature. Replace the

bulb and repeat the procedure twice before measuring the next gas.


Gas used in experiment = ________________

Mass of empty bulb = m = ______________ g

Ambient Pressure = P = ________________ kPa

Ambient Temperature = T = ________________ K

Sr # Volumeof gas

V

Mass ofgasm

(ml) (g) (g/gmol)

123

45


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EXPERIMENT # 9CRITICAL POINT OF A SUBSTANCE

OBJECTIVE:

Determine the critical point of given gas.

PROCEDURE :

The hoses in the water circulating system between the temperature-

controlled bath and the temperature control jacket of the critical

point apparatus must be secured with hose clips. The flow of water

to the temperature control jacket of the device on the lower hose

connection tube (hose olive) is adjusted with a pinchcock in such a

manner that just as much water can enter the device as can flow

out of the upper hose connection tube. If this adjustment is not

made, it is possible that water will flow out of the temperature

control jackets lid. During the measurement of an isotherm perform

a reading of the pressure every 0.1 ml of volume difference.


Gas used in experiment = ________________

Ambient Pressure = P = ________________ kPa


Sr#

Volumeof gas

V

Isotherm

10CP

Isotherm

20CP

Isotherm

30CP

Isotherm

40CP

Isotherm

50CP

(ml) MPa MPa MPa MPa MPa

1234

5EXPERIMENT # 10


29/34

ENTHALPY OF VAPORIZATION OF PURE LIQUIDOBJECTIVE:

Determine the enthalpy of vaporization of given pure liquid.

PROCEDURE :

Place the clean and dry evaporation vessel in an Erlenmeyer flask

and fill it through the straight inlet tube with 15 ml of the liquid to

be evaporated using a syringe with a cannula. Following this, attach

a 5 cm length of rubber tubing to the air inlet tube and connect it to

the air control valve. Only then, close off the right-angled air outlet

tube with a rubber cap to prevent loss of substance due to

vaporization. Subsequent to this, determine the mass of the

evaporation vessel, which has been thus prepared (weighing

accuracy: 0.0001 g). The Erlenmeyer flask serves merely as a

support for the evaporation vessel. Fill the calorimeter with 900 g of

distilled water which is at room temperature (weighing accuracy =

0.1 g). Put the oval magnetic stirrer bar into the calorimeter and

switch the magnetic stirrer on (Caution: Do not mistakenly switch on

the heating unit!). Insert the heating coil, the temperature probe

and the evaporation vessel into the lid of the calorimeter and fix

them in position. Take off the rubber cap and connect the

evaporation vessel to the filter pump via the safety bottle.

Wait until a temperature equilibrium has been reached

(approximately 10 min). Ensure that the equilibrium temperature

has been reached in the calorimeter, i.e. the temperature remains

constant or shows only a slight drift, then turn on the water jet


30/34

pump and start the vaporization process by carefully opening the air

control valve on the air inlet. Avoid vigorous sputtering and delayed

boiling. When the temperature of the water has decreased by

approx. 1C, close the air control valve and shut off the water jet

pump (let air into the safety bottle!). Immediately remove the

vacuum tubing from the air outlet tube of the evaporation vessel

and close this outlet tube with the rubber cap. Continue to measure

and record the temperature of the system until a new equilibrium

has Now, perform electrical calibration to determine the total heat

capacity of the calorimeter. To do this, supply 10 V AC to the work

and power meter for the electric heating. Put the free ends of the

heating coil connection cables into the output jacks. The system is

now continuously heated and the supplied quantity of energy is

measured. When the work and power meter shows approximately

4000 Ws, switch off the heating and read off the exact quantity of

electrical energy that has been supplied. Continue to measure for

another three minutes been reached or until the alteration only

occurs slowly and linearly.

Subsequently remove the closed evaporation vessel, carefully dry it,

then weigh it in the Erlenmeyer flask which was previously used.

From the two weighings, i.e. before and after vaporization, the

quantity of vaporized substance can be calculated. Always

thoroughly clean and dry the evaporation vessel before performing

a new measurement.


31/34



Mass of empty flask = m = ______________ g


Electrical work = Wel =______________W-s

Sr

#

Mass ofvaporiz

edsubstan

cem

FinalTemperat

ure ofvaporizati

on

T

V

Enthalpy ofvaporization

Entropy ofvaporizati

on

(g) (g) (g/gmol)

123

TV = Temperature difference during vaporization

Tel = Temperature difference during calibration

Wel = Electrical work

n = Quantity of vaporized substance (m/M)


32/34

EXPERIMENT # 11

ENTHALPY OF MIXING OF MIXTURE

OBJECTIVE:

Determine the enthalpy of mixing of a binary mixture.

PROCEDURE :

For the first measurement, fill 432 g water into the calorimeter.

Insert the oval magnetic stirrer bar in the calorimeter and switch the

magnetic stirrer on (Caution: Do not switch on the heating unit by

mistake!). Insert the heating coil and the temperature probe into the

lid of the calorimeter and fix them in position. Weigh 154 g of

acetone in a 250 ml Erlenmeyer flask. Cut a rubber stopper with

hole lengthwise, put the second temperature probe through the hole

and close the Erlenmeyer flask before hanging it into the

temperature-controlled bath. Adjust the immersion thermostat to

the temperature of the water in the calorimeter and wait until the

temperature difference between the acetone in the bath and the

calorimeter does not exceed 0.02 K. Wait a few minutes, then pour

the acetone into the water in the calorimeter. After new

temperature equilibrium has been reached, perform electrical

calibration for the determination of the total heat capacity of the

calorimeter. To do this, supply 10 V AC to the work and power meter

for the electric heating. Put the free ends of the heating coil

connection cables into the output jacks. The system is now

continuously heated and the supplied quantity of energy is

measured. When the temperature increase in the calorimeter


33/34

induced by the electrical heater is approximately equal in size to the

temperature change resulting from mixing the two liquids, switch off

the heating and read the exact quantity of electrical energy

supplied. Continue to measure for another three minutes


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Mass of empty flask = m = ______________ g


Electrical work = Wel =______________W-s

Sr

#

Massof

watermw

Mass ofAcetone

ma

Tcal

SpecificEnthalpy of

mixing

TotalEnthalpy of

mixing

(g) (g) (KJ/gmol)

123

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