# Physical Chemistry

Paper: III

* PHYSICAL CHEMISTRY* M. Marks: 50

**Gaseous state:**

Kinetic molecular model of a gas; collision frequency, collision diameter, mean free path, and viscosity of gases, including their temperature and pressure dependence, relation between mean free path and coefficient of viscosity, calculation of s from h ; Barometric distribution and its use in the determination of Avogadro's number, Maxwell distribution of velocities and its use in evaluating molecular velocities (average, root mean square and most probable) and average kinetic energy, law of equipartition of energy, degrees of freedorn and molecular basis of heat capacities. Behaviour of real gases: Deviations from ideal gas behaviour, compressibility factor, Z, van der Waals equation of state, its derivation and application in explaining real gas behaviour, virial equations of state; van der Waals equation expressed in virial form and calculation of Boyle temperature. Isotherms of real gases and their comparison with van der Waals isotherms, continuity of states, critical state, relation between critical constants and van der Waals constants, law of corresponding states. Intermolecular forces: Dipole moment and molecular polarisability, dipole-dipole, dipole-induced dipole, induced dipole-induced dipole,interactions; electrical origin of nonideal behaviour.

**liquid State:**

Qualitative treatment of the structure of the liquid state; Radial distribution function; physical properties of liquids; vapour pressure, surface tension and coefficient of viscosity; qualitative discussion of structure of water.

**Chemical Thermodynamics:**

Intensive and extensive variables; state and path functions; isolated, closed and open systerns; zeroth law of thermodynamics.

First law: Concept of heat, q, work,w, internal energy, U and statement of first law; enthalpy, H, relation between heat capacities, calculations of q, w, U and H for reversible, irreversible and free expansion of gases (ideal and van der Waals) under isothermal and adiabatic conditions. Thermochemistry: Heats of reactions: standard states; enthalpy of formation of molecules and ions and enthalpy of combustion; calculation of bond energy, bond dissociation energy and resonance energy from thermochemical data, effect of temperature (Kirchhoff's equation) and pressure on enthalpy of reactions.

Second Law: Concept of entropy, thermodynamic scale of temperature: statement of the second law of thermodynamics: molecular and statistical interpretation of entropy. Calculation of entropy change for reversible and irreversible processes. Third Law: . Statement of third law, concept of residual entropy; calculation of absolute entropy of molecules. Gibbs and Helmholtz energy; variation of S,G, A with T, V, P; relation between Joule-Thomson coefficient and other thermodynamic parameters; inversion temperature; Gibbs-Helmholtz equation: Maxwell relations; thermodynamic equation of .state.