Chem 111-internal 2004

Universal Science College Internal Examination Subject: Chem 111 (Physical Chemistry) Date: Feb 16, 2005

(B. Sc. Biochemistry) First Semester 2005

Full Marks: 100 Pass Marks: 45 Time: 3 hours

Candidates are required to give their answers in their own words as far as practicable. The figure in the margin indicates the full marks. Group A Long Questions (Any three ) (3× ×14 = 42) 1. Derive vander waal's equation of state. How does vander waal equations show deviation with temperature and pressure. 2. Define transport number. How is transport number determined using Hittorf's method. 3. What do you mean by simultaneous reaction? Derive an expression for integrated rate equation of consecutive reaction. 4. State and explain second-law of thermodynamics. Derive an expression for entropy change of mixing. Group - B Short Questions: (Any six) (6× ×7 = 42) 1. Explain how molecular weight is determined by viscosity method (using ostwald viscometer). 2. Explain the methods of preparation of sol by peptization and colloidal mill. 3. Show that degree of dissociation of an electrodyle is diretly proportional to the square root of dilution. Mention the causes why ostwald's dilution law is not applicable for strong electrolyte. 4. The specific conductance of saturated solution of Ag Cl at 180 C is 1.24 x 10-6 mho cm-1 after substracting that of water. The mobilities of Ag+ and Cl- ions at this temperature are 53.8 and 65.3 respectively. Calculate the solubility of Ag Cl in grams per litre. The equivalent weight of Ag Cl is 143.5. 5. Describe the collision theory for Bimolecular reaction. What are the weakness of this theory? 6. Define specific rate constant. Derive an expression for first order rate constant. 7. How are work function and free energy related? Write the criteria of spontaneity of a chemical reaction. 8. (a) Calculate the change in free energy for the expansion of one mole of an ideal gas from 20 atm to 0.2 atm at 250 C. (b) Calculate the entropy change in the evaporation of a mole of water at 1000 C. Latent heat of Vaporization = 540 Calg -1 Group – C Very short questions: (Any eight) (2× ×8 = 16) 1. Define Gold number. 2. Calculate the root mean square velocity of CO2 at 270 C. 3. Define collision frequency and mean free path. 4. The equivalent conductance of NH4Cl at infinite dilution is 149.7 mho, for NaoH is 247.8 mho and NH4Cl is 126.45 mho at 250 C. Calculate the equivalent conductance for NH4OH in mho at infinite dilution at the same temperature. 5. Explain why equivalent conductance increases and specific conductance decreases with dilution. 6. Mention the units of resistance, conductance, equivalent conductance and specific conductance. 7. Define order and molecularity. 8. Half life period for a first order reaction is 25 min. Find the time required for the completion of 90% reaction. 9. Write the characteristics of enzyme catalysis. 10. Define entropy. 11. State third law of thermodynamics 12. Define chemical potential. ***