LOYOLA  COLLEGE (AUTONOMOUS), CHENNAI-600 034.

B.Sc. DEGREE  EXAMINATION  – chemistry

third  SEMESTER  – APRIL 2003

CH  3500/ che 504 physical chemistry – I

04.04.2002

1.00 – 4.00                                                                                          Max: 100 Marks

 

 

 

PART – A                                         (10 ´ 2 = 20) )

Answer ALL questions

 

1. What is an adiabatic process?
2. Examine whether dP is a complete differential for a system with the equation of state P(V-b) =RT where b,R are constats.
3. State: Trouton’s law.
4. What is the effect of pressure on the gaseous system PCl₅ PCl₃+Cl₂ at equilibrium?
5. Define enthalpy of combustion.
6. Mention the importance of the following.

(i)  plait point          (ii) tie line.

7. Calculate the number of components and degree of freedom in an aqueous solution

of Nacl.

8. Prove that a congruent melting point is an invariant point.
9. Define : Henry’s law.
10. Calculate the osmotic pressure of a 5% aqueous solution of glucose at 25°C

(mol.wt. of glucose=180 g mol^-1)

 

PART  – B                                         (8 ´5 = 40)

Answer any eight only

 

11. State and explain Hess’s law with an example.
12. Show that PV^r = constant.
13. 10 moles of an ideal gas expand isothermally and reversibly at 27°C from 10 lit to 100 lit. Calculate q, w, DE, DH and D
14. The standard free energy change of a chemical reaction at 100k is -10⁴

Calculate the equilibrium constant for the reaction.

 

15. Differentiate

• intensive and extensive variables.

(ii) bond energy and bond dissociation  energy.

16. How is absolute entropy of a gas determined using third law of thermodynamics?
17. State phase rule and discuss its derivation.

 

 

 

 

 

18. Explain the Pattinson’s process of desilverisation of lead.
19. Obtain a relation between osmotic pressure and uapour pressure lowering of an ideal solution.
20. State Raoult’s law and discuss it for a solution showing positive deviation.
21. The molar heat of vaporisation of water at 100°C is 40.585 kJ.  At what temperature

will a solution containing 5.60g of glucose per 1000g of water boil?(Mol. wt. of glucose = 180 gmol^–1)

 

 

 

PART  – C                            (4 ´ 10 = 40 Marks)

Answer any four only

 

22. Deduce four Maxwell’s equation from first principles. (10)
23. Derive (i) Kirchoff’s equation (5)

(ii) an expression for entropy of mixing of gases.                                    (5)

• a) For the reaction of the type

aA + bb cC +dD

derive the relation connecting DG and reaction quotient and deduce an expression for equilibrium constant.                                                                              (5)

 

1. b) Derive Gibbs-Helmboltz equation.  Mention its significance.                      (5)

 

25. State the distribution law. Discuss its thermodynamic derivation and explain

how it is altered during the association of the solute in one of the solvents.     (10)

 

26. Derive thermodynamically an expression connecting elevation of boiling point

of a solution and molality.

27. a) Discuss the salient features of the phase diagram of sulphur system.           (6)

 

1. How will you explain the variation of the mutual solubility of water and

phenol with temperature?                                                                              (4)

 

 

 

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