Physical Chemistry — DU B.Sc. (Prog.) Applied Life Sciences with Agrochemicals and Pest Management pertaining to Chemistry Previous Year Question Papers

(d) Calculate the pH of 10-8 M Hcl aqueous solution. 5. (a) Explain buffer action ifsmall amount ofNaoH or Hcl is added in basic buffer solution (NH40H/ (b) Write any two applications of solubility product. 80 mL of 1.3 X 10-3 M AgN03 is mixed with 20 mL of 4.5x 10-5 M Na2S solution. Will Precipitation occur (Ksp of Ag2S = 1.6 x 10-49)? (c) (i) What are the factors affecting the degree of ionization? (ii) Calculate the pH of 0.01 M NH40H. The dissociation constant of ammonium hydroxide is 1.8 x 10-5. (5,5,5) 6. Write short notes on the following: (a) Common Ion Effect and its Applications (b) Enthalpy of Combustion and its applications (d) Explain the Qualitative treatment of acid-base titration curves (e) Two statements of second law of thermodynamics (I) Kirchhoffs Equation (5x3) Pest Management 1. Answer the following questions in brief: (a) Distiiiguish between extensive and intensive properties. Give two examples for each (b) Define specific heat capacity, why specific heat capacity is considered as intensive property (c) One mole of an ideal gas undergoes isothermal and reversible expansion at a temperature of 300K, increasing its volume from 10 dm3 to a final volume of 20 dm3. Determine the work done, as well as the changes in internal energy (AE), enthalpy (AH), and heat transfer (8q). (d) Determine the concentration of H+ ions in rainwater with a pH of 5.7. (4,4,4,3) 2. (a)State and explain Kohlrausch's Law of independent migration of ions. Illustrate how this law is used for the calculation of equivalent ionic conductance at infinite dilution of weak electrolytes. (b) The heat of combustion of ethyl alcohol (C2H50H) is 1380.7 KJ/mol. If the heat of formation of C02 and H20 are 394.5 and 286.6 KJ/mol respectively. Calculate the heat of formation of Ethyl alcohol. (c) State Third law of thermodynamics. Derive expression for the entropy calculation of any (d) Define Integral and differential enthalpies of solution and dilution (4,4,4,3) 3. (a) State Le chatelier's principle. For the equilibrium reactions given below. Discuss how the equilibrium will shift with the change in temperatu.re and pressure : (b) Deduce the relation between Kh, Ka, Kb and Kw for the solution of a salt of a weak acid and weak base. Also, find the pH of the hydrolyzed salt solution. (c) Define acidic and basic buffers. Give one example for each. Calculate the pH of a buffer solution containing (Ka for acetic acid is 1.8X10-5). (5,5,5) I 4. (a)WhattherelationbetweenKpandKc. Giveone example for whicli Kp is equal to Kc. For the reaction 2S02(g) + 02(8) E± 2S03(g) Kp = 0.1 i atm-1 at 300 K. Find Kc. (b) Define Equivalent conductance and specific conductance. How are they related? Explain Why the specific conductance of a solution decreases with dilution, but molar conductance increases. (c) The equilibrium constant (Kp) for the reaction is 5.04xl0]7at 25°C. Calculate the standard free energy change for the reaction.