Chem 111-internal 2005

UNIVERSAL SCIENCE COLLEGE (B.Sc. Biochemistry)

First Semester 2006

Second Term exam Subject: Physical Chemistry (Chem. 111) Date: - 31st Jan. 2006

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 full marks.

Group – A (Any Three)

(3 X 14=42)

1. Describe the reasons of deviation of gas equation PV= nRT from ideal behaviour. Derive van der waals equation for real gases. Mention the significance of van der waals constants. 2. What is transport number? State Hittorf's rule and explain the principle involved as well as experimental method applied for the determination of transport number by Hittorf's method. 3. What are simultaneous reactions? Derive an expression for parallel reactions. 4. The specific reaction rates of a chemical reaction at 00c and 300 C are 2.45X 10-5 sec-1 and 16.2 X 10-4 sec-1 respectively. Calculate the energy of activation.( R= 8.314 JK-1 mol-1) 5. Define free energy? Derive an expression for Helmholtz equation in terms of enthalpy and free energy.

Group – B (Any Six)

(6 X 7=42)

1. Describe the principle and method applied for the determination of average molecular weight of macromolecules by osmometry. 2. van der waals constants for a gas X are a = 4.65 atm lit -2 and b = 4.08 ml mol-1. Find the critical temperature and critical pressure of the gas. 3. Write a short note on Debye- Huckel limiting law. 4. A solution of silver nitrate containing 10.0 gm of silver in 50 ml of solution was electrolyzed between platinum electrodes. After electrolysis, 50 ml of the anode solution was found to contain 9.0 gm. of silver, While 1.25 g of metallic silver was deposited on the cathode. Calculate the transport number of Ag+ and NO3- ions. 5. Mention the postulates of activated complex theory. On the basis of this theory, derive an expression for rate constant. 6. Discuss the intermediate compound formation and adsorption theory of catalysis. 7. Derive an expression for entropy of mixing. 8. Define entropy change in chemical reaction. Show that entropy of the universe tends toward maximum.

Group –C (Any Eight)

(8 X 2=16)

1. Why gases cannot be liquefied beyond a certain temperature whatever the pressure may be applied? 2. Calculate the root mean square velocity of a molecule of CO2 at 2000 C. 3. What are thixotropic gels? Give examples. 4. What is asymmetric effect? 5. Calculate the ionic strength of 0.1 M FeCl3 solution. 6. The equivalent ionic conductances of NaCl, NH4Cl and NaOH at infinite dilution are 126.5, 149.7 and 248.1 ohm-1 cm2 eqv-1 respectively. Calculate equivalent conductance at infinite dilution of NH4 OH. 7. Define order and molecularity. 8. Define chain reactions. 9. 40% of H2O2 decomposes in 8 minutes in an experiment. Find out its rate constant if it is first order reaction. 10. State third law of thermodynamics. 11. What is spontaneous process? 12. 4 mloles of an ideal gas expanded isothermally to 10 times its initial volume. Calculate the change in entropy.