inorganic reaction 2012 - part-1

7/28/2019 Inorganic Reaction 2012 - Part-1

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Inorganic Reactions Slide-01

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INTRODUCTION


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What is Chemistry ?

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CHEMISTRY IS THE SCIENCE OF MATTERS AND THEIRCHANGES, RELATED TO :

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Structure

Composition

Properties Energy


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ORGANIC CHEMISTRY :is the study of the structure, properties,

composition, mechanisms, and reactions

of organic compounds

INORGANIC CHEMISTRY :

is the study of the structure, properties,composition, mechanisms, and reactions

of inorganic compounds

CHEMISTRY


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Inorganic compounds may be classified by the

elements or groups they contain (e.g., oxides,sulfates).

The major classes of inorganic polymers are silicones,silanes, silicates, and borates.

Coordination compounds (or complexes), an importantsubclass of inorganic compounds, consist of moleculeswith a central metal atom (usually a transitionelement) bonded to one or more nonmetallic ligands

(inorganic, organic, or both) and are often intenselycoloured.

Until 1828, scientists believed that organiccompounds could be formed only by life processes.


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Since carbon has a far greater tendency to formmolecular chains and rings than do other elements, its

compounds are vastly more numerous (many millionshave been described) than all others known.

Living organisms consist mostly of water and organiccompounds : proteins, carbohydrates, fats, nucleic acids,

hormones, vitamins, and a host of others. Natural and synthetic fibres and most fuels, drugs, and

plastics are organic.

Hydrocarbons contain only carbon and hydrogen; organic

compounds with other functional groups includecarboxylic acids, alcohols, aldehydes, ketones, phenols,ethers, esters, and other, more complex, molecules,including heterocyclic compounds, isoprenoids, and

amino acids.


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THE SCOPE OF CHEMISTRY :

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INORGANIC CHEMISTRYORGANIC CHEMISTRY

BIOCHEMISTRY

ANALYTICALCHEMISTRY

PHYSICALCHEMISTRY

THEORETICAL DEVICES EXPERIMENTAL DEVICES


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Physical Chemistry

Physical chemistry is the study of macroscopic, atomic,subatomic, and particulate phenomena in chemicalsystems in terms of physical laws and concepts.

It applies the principles, practices and concepts of

physics such as motion, energy, force, time,thermodynamics, quantum chemistry, statisticalmechanics and dynamics.

Physical chemistry, is predominantly (but not always) amacroscopic or supra-molecular science, as the majorityof the principles on which physical chemistry wasfounded are concepts related to the bulk rather than onmolecular/atomic structure alone; for example, chemicalequilibrium, colloids.


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Analytical Chemistry

Analytical chemistry is the study of the separation,identification, and quantification of the chemicalcomponents of natural and artificial materials.

Qualitative analysis gives an indication of the identity of

the chemical species in the sample and

Quantitative analysis determines the amount of one ormore of these components. The separation ofcomponents is often performed prior to analysis.

Analytical chemistry is also focused on improvements inexperimental design, chemometrics, and the creation ofnew measurement tools to provide better chemicalinformation.


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ANALYTICALCHEMISTRY

PHYSICALCHEMISTRY

THEORETICAL DEVICES EXPERIMENTAL DEVICES

EXPERIMENTALOBSERVED FACTS

THEORETICALEXPLANATIONS


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http://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml

Scientific Method


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Kornhauser (1981)

It is not chemistry if we learn theorieswithout facts, and it is not science if welearn only facts without learning theories.

Theories must not replace facts inchemistry, but should explain them.


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CHEMICAL REACTIONthe focal point of any chemical studies

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Why do chemical reactionsoccur?

For the very essence of practical chemistryis the scientific control of chemical change.

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Before we can consider "Why" reactions occur, it isnecessary to think of what happens during theoccurring of a chemical reaction.

Reactants productsIn order for this to happen, atoms, which are initiallyattached to one another in a certain way in the

reactants, become separated, at least to some extent,and rearranged in the products.

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+


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+

REACTANTS ATOMIC GAS

SYSTEM

PRODUCTS


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h

E1 = mgh1

E2 = mgh2

Falling Ball : An Example


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Definition

THE CONCEPT OF ENERGY

Energy could be defined as the capacity ofa system to do work


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Work

Work = Force x Distance

w = F x (r2 r1)

w : work

F : force

r2 r

1: distance

F F

r1 r2

r2 r1


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w = F x (r2 r

1)

w = x A (r2 r1)

F

Aw = P x (V2 V1)

w = P x V

P


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v1 v2

Pex

P1

v1 v2

P2

w = Pex dV

Pex


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+

- v

F

HYDROGEN ATOMIC MODEL

r

q1q2

r2F = -


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U = F dr = - dro o

q1q2

r2

q1q2

r2F = -

q1q2

r

U = + ]o

q1q2

rU = -

q1q2

rU = -


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SYSTEM

Atomic Nuclei

Electrons

MOLECULES

ATOMS


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Atomic Nuclei nuclear binding energyElectrons electronic energy

Vibrations vibration energyRotations rotation energyTranslations translation energy

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SYSTEM

qheat

Wwork

The First Law of Thermodynamics :

In ordinary processes, energy is conserved, it isneither created nor destroyed


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q

WSYSTEMheat

work

If heat q is added to a system and work w is done bythe system, the total amount of energy added to thesystem, (q - w); is not destroyed but is stored withinthe system to increase the internal energyU

U


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Unuclear : nuclear binding energy MeV

Uelectronic : electronic energy eV

Uvibration : vibration energy cal/mole

Urotation : rotation energy cal/mole

Utranslation : translation energy cal/mole

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U = q - w

THE INTERNAL ENERGY : The total energy


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Daltons Atomic Theory

1. All elements are composed of sub-microscopic indivisible parts calledatoms.

2. Atoms of the same element are

identical, those of different atoms aredifferent.

3. Atoms of different elements combine inwhole number ratios to form

compounds.

4. Chemical reactions involve therearrangement of atoms. No newatoms are created or destroyed.


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Atoms of different elements combinein whole number ratios to formcompounds.

Chemical reactions involve therearrangement of atoms. No new

atoms are created or destroyed.

Chemical Energy :

The energy involved in chemical

reactions is in the range of severalelectron volt (1 eV = 23.06Kcal/mole)


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Considering that mechanical work w is equal to pV :

U = q - pV

U = qvmeasurable at constant volume

U : How to measure?


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Since most chemical processes proceed at constantpressure rather than at constant volume, it is more

convenient to use other new definition of internal energycalled enthalpy : H = U + pV or H =U + pV

U+ pV= qp

H = qpmeasurable at constant pressure


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The Second Law of Thermodynamics :

It is impossible to have chemical processes,

working with a 100 % efficiency. Somewaste energy must also be released.


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G =H - TS

Chemical

Bonding

System

Structuring

GIBBS FREE ENERGY


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CHEMICAL BONDING :

A Thermodynamic Perspective

A A BB

+


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ATRACTIVE ENERGY :

Between nucleus A and electron B

Between electron A and nucleus B

REPULSIVE ENERGY :

Between nucleus A and nucleus B

Between electron A and electron B

Uatt

= - Catt/r

Urep= + Crep/r


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Uatt

= - Catt/r

Urep= + Crep/r

U

r


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Uatt= - Catt/r

Urep= + Crep/r

U


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BOND ENERGY :

The energy required to break downchemical bond into separate atoms

BOND LENGTH :

The equilibrium distance between two

atoms involving chemical bond.


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INTERNAL ENERGY U :

The most stable chemical bond would beformed at the lowest internal energy

BOND ENERGY:

The stronger chemical bond would beformed with larger bond energy

BOND ENERGY vs INTERAL ENERGY


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EAB : Bond Energy

rAB : Bond Length

U

EAB

rAB


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Chemical processes tend to proceedspontaneously in the direction of diminishedfree energy, i.e. when the free energychange, G, is negative.

G is the driving force of

chemical processes


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G = H - TS

The Strength ofChemical Bond

The Degree of

Disorder of theStructure

THE DRIVING FORCE


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CHEMICAL BONDS

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CHEMICAL

BONDING

ElectrostaticApproach

Electron sharing

Approach

CoulombicForces

Sharing of

electron pair

+-


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normal

coordination

CHEMICAL

BONDING

Electrostatic

Approach

Electron

SharingApproach

Ionic Bond

Covalent Bond

Metalic Bond

Hydrogen Bond


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STRONGCHEMICALBONDS

WEAKCHEMICAL

BONDS

LARGEBONDENERGY

SMALLBONDENERGY

LOWINTERNALENERGY

HIGHINTERNAL

ENERGY

LOW

ENTHALPY

HIGHENTHALPY

~

~

~

~

BOND STRENGTH


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ENTROPY

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P, V, T P, V, T

ENTROPY EXPERIMENT


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MORE ORDRED

LESS ORDERED

LESS DISORDRED

MORE DISORDERED

LOWER ENTROPY

HIGHER ENTROPY


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S = ln

Boltzmanns Concept of Entropy :

Entropy

The Degree ofDisorder


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Principle-1 :Chemical processes tend to proceed spontaneouslyin the direction of diminished free energy, i.e. whenthe free energy change, G, is negative.

G = H - TSis the driving force ofchemical processes


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Chemical processes tends to proceed


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WEAKERBOND STRONGERBOND

LOWERENTROPY

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1. If the total bonding forces in the products exceed thosein the reactants and the total disorder (entropy) of theproducts is higher

REACTANTS PRODUCTS

Chemical processes tends to proceedspontaneously :


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G =H - TS

H < 0

S > 0 G < 0


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2. If the total bonding forces in the products exceed those in

the reactants and the total disorder in the products islower but not enough lower to make TS greater than H

REACTANTS PRODUCTSWEAKER

BOND

STRONGERBOND

HIGHERENTROPY

LOWERENTROPY


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G =H - TS

H < 0

S < 0 G < 0


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3. If the total bonding forces in the products are weaker thanthose in the reactants but the entropy increase (increase

in disorder) is more than large enough to compensate forthe heat absorbed.

REACTANTS PRODUCTS

STRONGERBOND WEAKERBOND

LOWERENTROPY

HIGERENTROPY


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G =H - TS

H > 0

S > 0 G < 0


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THE PRINCIPLES OF

ENTROPY

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Principle-2 :

The gaseous state is more probable than the liquidstate, which in turn is more probable than the solidstate

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SOLID LIQUID GAS

Entropy of Various Substances at 25 (in eu)


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Substance

Entropy Values at 25 (in eu)

Solid Liquid Gas

Sodium Na 12.30 13.83 36.71

Phosphorous P 9.82 10.28 38.98

Silicone Si 4.43 11.21 40.12

Lead Pb 15.50 17.14 41.89

Water H2O - 16.72 45.11

Methanol CH3OH - 30.30 56.80

Boron trioxide B2O3 12.91 18.55 64.42Silicone dioxide SiO2 10.00 11.35 54.62

Lithium oxide Li2O 898 9.86 56.03

Beryllium oxide BeO 3.38 10.50 47.21

Titanium oxide TiO2 12.01 15.43 56.44

Lead oxide PbO 15.59 20.55 57.35

Boron trichloride BCl3 45.30 - 85.30

Silicone tetrachloride SiCl4 - 57.20 79.20

Lead chloride PbCl2 32.50 38.34 76.63

Sodium chloride NaCl 17.33 20.22 54.88

Mercury bromide HgBr2 40.71 46.80 76.51

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Principle-3 :

A monatomic gas is more probable than a polyatomic

molecular gas, and hence tends to have higher entropy

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MOLECULAR STATE ATOMIC STATE

E f M i d P l i G


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H 27 .4 H2 15 6 - -N 36.6 N2 22.9 - -

O 38.5 O2 24.5 O3 19.0

F 37.9 F2 24.4 - -Si 40.1 Si2 17.5 - -

P 39.0 P2 26.1 P4 16.7

S 40.1 S2 27.3 S8 12.9

Cl 39.5 Cl2 26.6 - -

NO2 57 .5 N2O4 36.4 - -

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Entropy of Monatomic and Polyatomic Gas(in eu/g atom)


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Principle-4 :

An amorphous solid is more probable than acrystalline solid, and a simple crystalline solid is more

probable than a more complex crystalline solid

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CRYSTALLYNE AMORPHOUS


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Principle-5 :

A molecular addition compound, or acoordination complex, is less probable than

its separate components

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Cu(NH3)4SO4 Cu2++ 4NH3+ SO42-

H3N-BF3 NH3 + BF3


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Principle-6 :

Compounds or elements of higher atomic weight,or molecule of the free elements themselves, tend

to have higher entropy

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Principle-7 :

At ordinary temperatures, entropy effects are

commonly small enough to have relatively littleeffects on the direction of reaction, unless thedifference in total bonding energy between

reactants and products is relatively small.

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Before the concept of entropy had been clearlyrecognized, the heat of a reaction (entalpy) wasthe sole factor determining the direction ofspontaneous reaction.

Entropy units are calories per degree per mole,and the entropy changes accompanying reactionare often only a few entropy units, whereas heats

of reaction are commonly more than a kilocalorieper mole.

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Comparison on the values of Enthalpies and of FreeEne gie of Fo m tion (in k l mole 1)


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Substances Hfo Gf

o T Sfo

H2O (l) - 57.80 - 54.64 + 3.16HCl (g) - 22.00 - 22.77 - 0.77

SO2 (g) - 70.96 - 71.79 - 0.83

H2S (g) - 4.82 - 7.89 - 3.67

H2Te (g) + 36.90 + 33.10 - 3.80KNO3 (c) - 117.16 - 93.96 + 23.20

Na2CO3 (c) - 270.30 - 250.40 + 19.90

Al2(SO4)3 (c) - 820.98 - 738.99 + 81.99

NH3 (g) - 11.04 - 3.98 + 7.06N2O4 (g) + 2.31 + 23.49 + 21.18

HNO3 (l) - 41.40 - 19.10 + 22.30

PH3 (g) + 2.21 + 4.36 + 2.15

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Energies of Formation (in kcal mole-1).


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Principle-8 :

All chemical reactions that increase the entropyoccur spontaneously at high enough temperatures

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H = Ho + Cp dT

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S = So + dTCp

T


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T (K)

Energy

H = f (T)

S = f (T)

TS = f (T)

TC

G > 0

G < 0

G = H - T S


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Reactions

Hfo Gf

o

kcal/mol kcal/mol

CCl4(g) + 2 H2O(g) CO2 (g) + 4HCl(g) - 41.2 - 61.2

SF4 (g) + 3 H2O (g) SO3 (g) + 6HF(g) - 45.0 - 75.9

CaO(c) + CO2(g) CaCO3(c) - 42.5 - 31.1

CH4(g)+2 O2 (g) CO2 (g)+ 2 H2O (g) - 191.8 - 191.4

AsCl3(l) +3 NaF(c) 3NaCl(c) + AsF3(g) - 24.7 - 31.7

AlBr3 (c) + PCl3 (g) AlCl3(c) + PBr3 (g) - 3.1 - 4.3

CH3OH(l)+NH3(g) CH3NH2(g) + H2O(g) + 3.5 - 4.3

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Comparison on the Values of Standard Enthalpiesand of Free Energies for Some Chemical Reactions


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CaO(c) + CO2(g) CaCO3(c)

Ho = - 45.0 kcal/mole Go = - 31.1 kcal/mole

TS =H -G

TS = - 45.0 - 31.1 kcal/moleTS = - 13.9 kcal/mole

Standard enthalpy at 25oC Standard free energy at 25oC

S 46 4 cal mole-1 K-1

inorganic reaction 2012 - part-1

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