LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – CHEMISTRY
SIXTH SEMESTER – APRIL 2007
CH 6600 – MOLECULAR DYNAMICS
Date & Time : 16.04.2007/9.00-12.00 Dept. No. Max. : 100 Marks
Answer ALL questions. (10 ´ 2 = 20 marks)
- Define (i) particle (ii) wave
- Bring out the difference between photoelectric effect and Zeemann effect.
- Determine the Eigen value for “Ae-ax for the operator (d/dx2)”.
- What is the condition for φ1 and φ2 to be orthogonal functions in the interval [a,b]
- Explain the difference between thermodynamic probability and mathematical probability?
- Explain phosphorescence in terms of spin multiplicity
- Define quantum yield of a photochemical reaction.
- Define steady state approximation. What is its advantage?
- What is residual entropy? Give an example.
- Calculate the number of ways of distributing 4 fermions among 8 energy levels.
Answer any EIGHT questions. (8 ´ 5 = 40 marks)
- Explain the energy distribution in black body
- An electromagnetic radiation of wave length 200Å is incident on a metal surface of threshold frequency 6.53×1014 Hz .Calculate the velocity of the electrons emitted.
- Calculate the wave length of the lowest energy of the Balmer
- Calculate the ground state energy of a π-electron in 1, 3-butadiene. (The C=C & C-C bond distances are 1.33 and 1.54 Å, respectively).
- Explain the concept of separation of partition
- Derive an expression for the translational partition function.
- Draw Jablonski diagram and indicate the difference between fluorescence and phosphorescence. Discuss also their difference with regard to transition (pathways), duration, and change in spin multiplicity.
- Mention the various factors affecting fluorescence and phosphorescence and discuss any two factors in detail giving one example each.
- Discuss the principle and working of Uranyl Oxalate Actinometer.
- Discuss the differences in the kinetics of the two photochemical reactions of H2 with Cl2 and H2 with Br2.
- Write Sackur-Tetrode equation and define the terms involved. Also explain how the translational entropy of a gas varies with (a) temperature (b) pressure (3+2)
- (a) Differentiate fermions and bosons statistically.
(b) Calculate the molar residual entropy of a crystal in which the molecules can adopt
24 orientations of equal energy at 0K. (3+2)
Answer any FOUR questions. (4 ´ 10 = 40 marks)
- Discuss, with a suitable diagram, the different types of lines produced in the emission spectrum of atomic hydrogen.
- Derive an expression for the energy of a particle in a one dimensional box on the basis of quantum mechanics.
- Derive an expression for the most probable distribution on the basis of classical statistics.
- Discuss the mechanism and kinetics of the photochemical reaction between H2 and Br2.
- Mention the different types of quenching and derive Stern-Volmer equation for bimolecular quenching. (3+7)
- Mention any four relaxation techniques and derive an expression for relaxation time for a reaction involving equilibrium A = B (both I order) using temperature-jump method. (2+8)
* * * * *
SOME USEFUL CONSTANTS:
- Planck’s constant = 6.625 x 10-34 Js
- Boltzmann constant = 1.38 x 10-23 JK-1
- Velocity of light = 3 x 108 ms-1
- Avogadro number = 6.023 x 1023
- Rydberg constant = 1.097 x 107 m-1
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