2ed Semester Examination June 2011
Physical Chemistry (Electrochemistry, Molecular Spectroscopy
and Quantum Chemistry) Examination for the 3rd Year
Chemistry Special
Page 1 of 2
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Answer Five Questions Only of the following:
1 a) If you have the cell representation: Cu,CuSO (0.01M) //CuSO (0.1M),Cu 4 4
i) Refer to the type of the cell
ii) Calculate the E.M.F. of the cell, knowing that:
e (Cu /Cu) 0.34V 0 ++ = +
[21 marks]
[7 marks]
[14 marks]
b) Deduce the Nernst equation for the reaction: A B A B + z+ ↔ z+ + [21 marks]
2 a) Discuss briefly the amalgam concentration cells referring to both cathodic and
anodic reactions and the net reaction.
[21 marks]
b) Consider the cell: Pb, Pb++ (a =1) // Ag+ (a =1), Ag
where 0
red e for Pb = -0.126 V and 0
red e for Ag = +0.799 V
Write the cell reaction, then calculate the E.M.F. and ΔG° of the cell.
[21 marks]
3 a) If HCl35.5 molecule absorbs at 3000 cm-1. Deduce type of radiation and spectra if
intermolecular distance is 100 pm. Calculate the frequency of vibration.
[21 marks]
b) What is the expected type of the electronic spectra of the following compounds?
In which region could be the spectra expected? Which one of them is colored and
why?
[21 marks]
CH CH CH CH = CHCOOH 3 2 2
4 a) Give reasons for:
i. Vibration spectrum consists of one line.
ii. The energy of n→σ * transition decreases as the following order: CH3Cl >
CH3OH > CH3NH2.
iii. In Raman spectra molecules need not have dipole moment.
iv. Quantum restrictions are not significant for transitional excitation.
v. The vibration spectrum is characteristic of molecule or a group within it.
vi. Rotational spectrum consists of equally spaced lines in microwave region.
[24 marks]
[4 marks]
[4 marks]
[4 marks]
[4 marks]
[4 marks]
[4 marks]
Sohag University
Date: 15-06-2011
Chemistry Dep.
2ed Semester Examination June 2011
Physical Chemistry (Electrochemistry, Molecular Spectroscopy
and Quantum Chemistry) Examination for the 3rd Year
Chemistry Special
Faculty of Science
Time: 3 hours
Code: 322 Ch
Page 2 of 2
4 b) Calculate the number of degrees of freedom for the different molecular thermal
motions of NH3 and their energies in terms of KT at 25 °C
[18 marks]
5 a) Select All the correct answers (Justify your answer):
i. What is the eigenvalue of the momentum operator
dx
Px ih
∂
= −
∧
with
eigenfunction ikx e ?
A. ik B. − ikh C. kh D. ikx E. ikx e
ii. If the wave function ψ(x) satisfies the equation
3
2
( ) ( ) * π
∫ ψ ψ = +∞
−∞
x x dx , which of
the following wave functions is normalized?
A. ( )
3
2
ψ x
π
B. ( )
2
3
ψ x
π
C.ψ (x) D. ( )
3
2
ψ x
π
E. ( )
2
3
ψ x
π
iii. What are the properties of stationary state wave function?
A. Finite B. Continous C. Single Valued D. Hermitian E. Re al Valued
iv. An electron moves in a one-dimensional square well with size L, where the
potential energy is zero in the interior and infinite potential energy at the walls,
has a ground state energy E0. If the size is decreases to L/2 what is the new
ground state energy?
A. Zero B. / 2 0 E C. / 4 0 E D. 0 E E. 0 4E
v. What does De Broglie relation state?
A.
mv
h
mc
h λ = = B.
m
vh
m
ch λ = = C.
h
mv
h
mc λ = = D. = (n+1)
c
h λ E. ( +1)
Ρ
= n
h λ
[30 marks]
[6 marks]
[6 marks]
[6 marks]
[6 marks]
[6 marks]
b) For the particle in a ring in ground state, if the particle vector extending from φ=0
to φ=2π. What is the probability of finding the particle in half of the ring?
[12 marks]
6 a) Using secular determinant, calculate the energy of the π molecular orbitals of allyl
cation ( 2 2 CH = C H = CH
+
). Sketch the molecular orbital diagram.
[20 marks]
b) If the C-C bond stabilization energy is -230 kJ/mole, calculate the delocalization
energy in 1,3-butadiene molecule relative to ethene molecule.
[22 marks]
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Physical Constants: NA = 6.022×1023 mol-1, π = 3.142, R = 8.3145 JK-1 mol-1, h = 6.626×10-34 J.s amu =
1.66056 × 10-27 kg, F = 96500 coulomb, kB = 1.38066 × 10-23 J.K-1, me=
9.109×10-31 kg.
With all best wishes
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