IGNOU CHE-04 - Physical Chemistry

1. (a) Express the height of mercury column and density of mercury in SI Units. (b) Differentiate between lyophilic and lyophobic sols. 2. Derive the following equation for the collision frequency: 3. Show that for real gases 4. (a) Discuss the factors affecting surface tension of liquids. (b) Arrange the following in the increasing order of their viscosity: Glycerol, Benzene, Water Give reason for your answer. 5. Draw and name fourteen Bravais lattices. 6. Show that for a reversible adiabatic process, TV γ -t is constant. 7. Calculate the standard enthalpy of formation of acetone vapour and acetone liquid. (Enthalpy of vapourisation of liquid acetone is 29 kJ mol-1). 8. Write all the statements of the second law of thermodynamics. 9. The free energy change ΔG for a reaction is -221.00 kJ mol-1 at 298 K and -201.00 kJ at 318 K. Calculate the enthalpy change for the reaction at 308 K. 10. Discuss the boiling point-composition diagram of a liquid mixture showing positive deviation from Raoult’s law. 11. Discuss the principle of steam distillation. Also draw a suitable diagram for this process. 12. Briefly discuss van’t Hoff’s laws of osmotic pressure. 13. Draw and explain the phase diagram for KI-H2O system. 14. Derive the following equation: 15. Show that for the hydrolysis of a salt of a weak acid and a weak base, 16. What is transference number? Discuss the Hittorf method of determination of transport number. 17. What is standard hydrogen electrode? Explain with the help of a suitable diagram. Give the IUPAC rules for the sign convention in reporting the standard state half cell potentials. 18. For a second order reaction, show that Also give one example of such a reaction. 19. What is quantum efficiency. Explain its calculation using chemical action meters. 20. Explain the following terms: (i) Peptisation (ii) Dialysis.

1. (a) Write the SI units and its symbols for the following quantities: (i) Molar mass (ii) Force (iii) Pressure (b) How can we differentiate between oil in water and water in oil emulsions? 2. Draw the distribution of molecular speeds of gases. Write expressions for different types of speeds. Also calculate the average speed of oxygen molecules at 298 K. 3. Discuss Linde’s method of liquefaction of gases using a suitable diagram. 4. Define vapour pressure. Explain how is it measured? Which are will have lower vapour pressure-water or ethanol? Explain. 5. Briefly explain the terms ‘lattice’ and ‘basis’ giving suitable diagrams. 6. (a) “Work can be done in a variety of ways”. Explain. (b) Derive the following relation: C p – C v = nR 7. (a) Derive Kirchoff’s equation. (b) Explain what happens when the value of (i) is zero (ii) is constant (iii) changes with time. 8. Show that for a cyclic process of isothermal irreversible expression and reversible compression, show that the total entrophy change entropy is greater than zero. 9. (a) What is the free energy change when 2 moles of an ideal gas expands reversibly and isothermally at 3.20 x 10 2 K from an initial volume of 10.00 x 10 -2 m 3 to 2.00 m 3? (b) Derive the following relation: 10. Draw and explain the vapour pressure curves of a solution showing negative deviation from Raoult’s law. 11. Derive the following expression: for the mass of an organic compound that remains unextracted after n extractions. 12. (a) Discuss Rast method for determining the relative molecular mass of a non-volatile solute. (b) An aqueous solution contains 2 x 10 -3 kg of a solute is 5.00 x 10 -2 kg of water. Themolecular mass of the solute is 0.0540 kg mol-1. Calculate the change in freezing point if ice melts at 273.15 k and its molar enthalpy of fusion is 6021 J mol -1. 13. Discuss the phase diagram of sulphur giving a suitable diagram. 14. (a) Calculate the Kp for the following reaction. H2O + CO (g) = H2 + CO2 At equilibrium 15. (a) For 0.20 M solution of sodium acetate. Calculate the following at 298 K (i) Kn (ii) degree of hydrolysis (iii) pH (Kw = 1.0 x 10 -14 and Ka acetic acid = 1.8 x 10 5) 16. (a) Define molar conductance and give its units. (b) How can the solubility of a sparingly salt be determined using conductance method. 17. Discuss different types of electrodes giving one example of each. 18. Briefly explain various experimental methods of studying reaction rates. 19. For the photochemical reaction between H2 and Br, show that 20. (a) Differentiate between number average and mass average molar masses. (b) Calculate the mass average molar mass of molar mass a sample having following distribution.