1. Thermodynamics - I Unit-I 2nd semester Suggested Books:
An introduction to Chemical Thermodynamics by Rastogi and Mishra
Physical Chemistry, vol 2 by K. L. Kapoor
Physical Chemistry by Peter Atkins, Oxford University Press, Oxford
Physical Chemistry by Ira N Levine Tata McGraw Hill Education Pvt. Ltd.

2. Thermodynamics
The branch of science dealing with the relations between energy, heat, work and accompanying changes in the nature and behavior of various substances around us is called thermodynamics.
Thermodynamic terms.
System: A system is a portion of the universe which is selected for investigations.
Surroundings: The rest of the universe, which can interact with the system, is called surroundings.
Boundary. The space that separates the system and the surroundings is called the boundary.
Types of system
Open system: It is a system which has permeable boundary across which the
system can exchange both the mass (m) and energy (U) with the surroundings.
Closed system: It is a system with impermeable boundary across which the
system cannot exchange the mass (m) but it can exchange energy (U) with the
surroundings.
Isolated system: It is a system with rigid and adiabatic boundary across which
neither exchange of mass (m) nor energy (U) between the system and the
surroundings is not permissible.

3. Important terms and definitions
Extensive property: A property which depends directly on the size of the system is called extensive property. Volume, mass and amount (mole) are extensive properties.
Intensive property: A property which does not depend on the size of the system is called intensive property. Density, temperature and molarity are intensive properties.
State variables of the system: A system can be described by its measurable properties such as temperature (T), pressure (P), volume (V) and amount are called state variables.
State Function: A property of the system which depends only on the state variables and hence only on the initial and final states of the system is called state property or state function (energy (U), enthalpy (H), entropy (S), work function (A), free energy (G), volume (V), pressure (P) and temperature (T) are state functions)
Path function: A thermodynamic quantity is called a path function if its value depends on the path followed (work done)

4. Mathematical formulation of state property (Φ) : Φ = Φ (x, y)
The total differential of a state function is an exact differential.
Euler’s reciprocity relation
Thermodynamic process:
Isothermal process: A process is said to be isothermal when the temperature of the system is
kept constant, (dT = 0)
Adiabatic process: A process is said to be adiabatic if there is no exchange of heat (q)
between the system and surroundings during various operations. That is, q = 0
Isobaric process: A process is said to be isobaric if the pressure remains constant during the
change. (dP = 0)
Isochoric process: A process is said to be isochoric if the volume of the system remains constant during the change. (dV = 0)
Reversible process: A process is said to be reversible if the change can take place in both the forward and back directions by a small change in its state variables.
Irreversible process: A process is said to be irreversible if the change takes place in one direction.
Cyclic process It is a process in which the initial state of the system is restored after undergoing a series of changes

5. Concept of internal energy, work and heat
U: Internal energy is a characteristic property of a system which decides its nature and
behaviour. It is equal to the energy possessed by all its constituents namely atoms, ions and molecules. (Extensive and state properties)
W : work = – P×ΔV
Work done under isothermal irreversible condition
Work done under isothermal reversible condition
Reversible work of expansion is the maximum work which can be obtained from a system.
q: The change in the internal energy of the system due to difference of temperature of the system and its surroundings is called heat
When heat is absorbed by the system its energy increases. That is, ΔU is positive. Such a change is called endothermic.
When heat is given out by the system its energy decreases. That is, ΔU is negative. Such a
change is called exothermic.

6. zeroth law of thermodynamics : THERMAL EQUILIBRIUM
if two systems A and B are separately in thermal equilibrium with a third system C, then A and B will also be in the thermal equilibrium with each other.
THE FIRST LAW OF THERMODYNAMICS
Energy can be neither created nor destroyed. If it disappears in
one form it must reappear in some other equivalent form.
ΔU = q + w
Difficulties in the experimental determination of ΔU :  Need of a new thermodynamic property- the enthalpy : H = U + PV : Enthalpy: State function. Extensive property
Comparison of ΔH and ΔU
enthalpy change and heat exchanged at constant pressure
Heat capacity : The quantity of heat needed to cause unit rise in the temperature of
a substance is called its heat capacity
Heat capacity = Heat needed/Increase of temperature
Molar heat capacity: It is defined as the quantity of heat needed to cause unit rise in the temperature of one mole of a substance. Molar heat capacity is denoted by Cm.
Specific heat capacity: It is defined as the quantity of heat needed to cause unit rise in the temperature of unit mass of a substance

7. Heat capacity at constant volume
Heat capacity at constant pressure
Relation between CP and CV : Cp – CV = nR
Joule’s Law :
Joule – Thomson Coefficient :
Significance of Joule – Thomson coefficient μJ-T = (∂T/∂P)H
Joule-Thomson effect and the value of μJ-T form the basis of liquefaction of gases.
A positive value of the Joule-Thomson coefficient (μJ-T ) corresponds to a cooling effect
when a compressed gas is allowed to pass through small holes
A negative value of the Joule-Thomson coefficient (μJ-T ) corresponds to a heating effect
A zero value of the Joule-Thomson coefficient (μJ-T ) corresponds to no thermal change
Inversion temperature: The temperature at which the Joule-Thomson coefficient is zero is called the inversion temperature.

8. Calculation of w, q, ΔU and ΔH for isothermal and reversible changes in the states of an Ideal gas
Calculation of w, q, ΔU and ΔH for adiabatic and reversible changes in the states of an Ideal gas
Derivation of T–P–V relations for adiabatic and reversible process
Thermochemistry
The branch of chemistry dealing with the measurement and computation of energy changes (ΔU) and enthalpy changes (ΔH) of various types of physical transformations and chemical reactions is called thermachemistry.
Heat of a reaction
When the reaction is performed at constant volume the accompanying energy change
(ΔU) is called heat of reaction at canstant volume (qv)
ΔU = qv = Heat of reaction at constant volume
When the reaction takes place at constant pressure the accompanying enthalpy change
(ΔH) is called the heat of reactian at canstant pressure
ΔH = qp = Heat of reaction at constant pressure

9. Enthalpy of reaction (ΔrH)
.. is defined as the heat absorbed or liberated when the reactants are completely converted into products as represented by the balanced chemical equation at a given temperature and pressure
Standard enthalpy of formation (ΔfH0)
..is defined as the heat absorbed or liberated when one mole of a substance is formed from its constituent elements in their respective standard states. Standard enthalpy of formation is denoted by ΔfH0
Standard enthalpy of formation of an element is taken as zero
Standard enthalpy of formation of a gaseous atom :The heat absorbed when 1 mole of a gaseous atom is formed from its element in its standard.
Enthalpy of combustion (ΔcH): The enthalpy of combustion is the heat liberated at a constant pressure when one mole of a fuel is completely burnt in oxygen
Relation between standard enthalpy of reaction and standard enthalpy of formation
Enthalpy of neutralization
The heat liberated when one mole of hydrogen ions (H+) is completely neutralized by a base
in dilute aqueous solution at constant temperature and constant pressure is called enthalpy
of neutralization.

10. Hess's law of constant heats summation : The heat of a reaction (reaction enthalpy)
is the same whether the reaction takes place in one step or in several steps under the
same conditions.
Bond enthalpy: When a chemical bond is formed heat is liberated. This heat liberated at constant pressure is referred to as enthalpy of bond formation. On the other hand, the heat needed to cause the breaking of a chemical bond at a constant pressure is called the bond dissociation enthalpy.
Bond enthalpy of a diatomic molecule
Enthalpy of bond dissociation in polyatomic molecules
Enthalpy of atomization: The enthalpy change in converting one mole of a substance into its constituent atoms in gaseous states is called the enthalpy of atomization or heat of atomization of that substance.
Enthalpy of vaporization: The quantity of heat absorbed for complete conversion of one mole of a liquid in to vapour at its boiling point is called its enthalpy of vaporization.
Enthalpy of fusion: The quantity of heat absorbed for complete conversion of one mole of solid into liquid at its melting point is called its enthalpy of fusion.
Enthalpy of sublimation: The quantity of heat absorbed for complete conversion of one mole of solid directly into vapour is called enthalpy of sublimation or heat of sublimation

11. Temperature dependence of reaction enthalpy (Kirchhoff’s equation)
Derivation of Kirchhoff’s equation
Differential form of Kirchhoff’s equation
Integrated form of Kirchhoff’s equation
Acknowledgment :
An introduction to Chemical Thermodynamics by Rastogi and Mishra