LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034  B.Sc. DEGREE EXAMINATION – CHEMISTRY

AD 09

FIFTH SEMESTER – NOV 2006

         CH 5500 – PHYSICAL CHEMISTRY – II

(Also equivalent to CHE 508)

 

 

Date & Time : 25-10-2006/9.00-12.00         Dept. No.                                                       Max. : 100 Marks

 

 

 

PART – A

Answer ALL questions.                                              (10 ´ 2 = 20 marks)

 

1. Write the anodic reaction of SCE.
2. Define concentration cell. Give an example for concentration cell without
   transference.
3. Derive the relation between emf and equilibrium constant.
4. Calculate the ionic strength of 0.01 m MgCl₂.
5. Explain how the use of KCl minimises liquid junction potential.
6. Differentiate order from molecularity.
7. What is the role of a catalyst in a reversible reaction?
8. “Adsorption if spontaneous must be exothermic”. Explain.
9. Calculate the value of one Einstein for a radiation of wavelength 300 nm.

(Use SI units).

10. The half life of a reaction is doubled on doubling the initial concentration.
    Deduce the order of the reaction and the units of rate constant.

 

PART – B

Answer any EIGHT questions.                                   (8 ´ 5 = 40 marks)

11. Explain an experimental method of determining the standard reduction potential
    of Zn electrode.
12. Explain the construction and working of Weston saturated cell.
13. Calculate the emf of the following cell Zn/Zn²⁺(0.05 m)½½Zn²⁺(0.005 m)½Zn.
14. How will you determine the K_sp of Ag₂CrO₄?
15. Explain the working of lead storage cell.
16. Mention Debye–Huckel equation. How will you verify it experimentally?
17. Derive an expression for the rate constant of a II order reaction with unequal
    concentrations ofHowH

reactants.

18. Explain the steps involved in thermal chain reactions with special reference to the
    dissociation of ethanal.  Indicate the rate expression for each step.
19. At 378.5° C the half life period for a I order reaction is 363 min and E_a is
    52 kcal/mol.  Calculate the time required for the reactant to be 75% decomposed
    at 450° C(R = 2 cal K^–1 mol^–1).
20. How is surface area of a solid determined using adsorption studies?
21. Explain “Skrabal” plots.
22. The decomposition of NH₃(g) on a tungsten filament follows first order kinetics
    at low pressure and zero order kinetics at high pressure.  Explain.
23. Explain “photosensitation” with two examples.

 

 

 

 

 

PART – C

Answer any FOUR questions.                                                (4 ´ 10 = 40 marks)

 

24. Explain any five types of electrodes. Derive expression for EMF of each of them.

25.(a) Explain the derivation of Nernst equation.

(b) Calculate the emf of Cu½Cu²⁺ (0.01 m) electrode at 25° C.

(Cu½Cu²⁺ : SRP = 0.34 V)

26. Explain the following

(a)  Determination of K_a of a weak acid by conductometric method.

(b)  Conductometric titration of a mixture of HCl and CH₃COOH  vs  Standard

NaOH.

27. Explain how the kinetic parameters for a single substrate enzymatic reaction can
    be obtained.
28. Explain the principle of “flash photolysis” with a block diagram.
29. Mention the postulates of ARRT and explain how the expression for rate constant
    can be obtained from ARRT.

 

 

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