cs mains 2010 CHEMISTRY Paper-I
Time Allowed Three Hours Maximum Marks · 300


Section-A
1. Deduce the following equation for a particle in a one-dimensional box giving the Hruniltonian explicitly <img src='./qimages/786-1a.jpg'> Also deduce the energy for the system. 15
Using VSEPR theory 1 predict the shapes of PC1 2 F 3 and SF 4 . Indicate the state of hybridisation in each case. 15
How do you account for the fact that the rate of reaction is more than double for a ten degree rise of temperature, whereas the number of collisions increases by only for the same rise of temperature? 15
What are meant by phase, component and degree of freedom? Define Gibbs phase rule. A saturated solution of sodium sulphate with excess salt is at equilibrium with its vapour in a close vessel. How many phases components and degrees of freedom are there in the system? 10+5·

2. Draw the MO energy-level diagrwn for N 2 and 0 2 molecules. Predict their magnetic behaviours and also calculate the bond orders. 20

State the essential conditions for hybridisation. Show diagrrunmatically the possible geometries from hybridisation of p and d orbitals. Give examples. 10
Half-change time and initial
concentrations of a reaction are as
follows
t Y2 a (mm of mercury)
425 354
275 540
941 158
What is the order of the reaction? Calculate the rate constant.
Lindemann's mechanism for the firstorder reaction is given as follows <img src='./qimages/786-1c.jpg'> Under what· condition will the reaction show first order and second order? 20

3. A photochemical reaction with quantum efficiency of one shows no temperature dependence. Explain. 10
Calculate the number of moles of HCl(g) produced by the absorption of one joule of radiant energy of wavelength 480 nm in the reaction
H 2 +Cl 2 2HCl(g)
if the quantum yield of the photochemical reaction is 1 ·0 x 10 6. 10
Give the postulates on which Langmuir's adsorption isotherm is based. Derive the expression for Langmuir"s adsorption isotherm. How does this equation account for the adsorption at high pressure and low pressure? Show that when a diatomic gas adsorbs an atom on the surface of a solid the Langmuir adsorption isotherm is modified to

where,
TETA fraction of surface covered
K k adsorption
kdesorption
p pressure of gas 20
With proper diagrrun.?? calculate and explain briefly the limiting radius ratio values for tetrahedral and octahedral sites. 20

4. Draw the phase diagram of a simple eutec tic sy stem . Give an example of such a system. 20
Using the principle of LCAO,obtain the normalised wave fu nction s fo r the bonding and the antibonding molecular orbitals fo r H2+ system . 20
For the reaction
2N 0 +02 2N02
rate k[NOJ 2 2 2
Explain that the rate of this reaction decreas es with increa se of temperature . 10
How much will the rate of reaction change if volume of the ves sel is reduced to 1/3 of its original volume?10

Section-B

What are interhalogen compounds How are they classified? Give structu res of IF5 and IF7 . 15
How do you explain th e magnetic properti es of trans iti on metal ions Ln by the Crys tal Field Th eory? 15
Explain what are meant by extensive and inte nsive properties of a system.Which of the following properties are extensive and which are in tensive 15
Entropy
Gibbs fr ee energy
Vis cosity
Chemical p oten ti al
He at cap acity

What 1s meant by liquid-j unction p otential? Why is KCl salt brid ge used to eliminate it? Give one example of a concentration cell with transference. 15

6. What 1s meant by heat capacity Establish a relationship between he at cap acity at constant p ressure and constant volume i.e.<br><br> <img src='./qimages/786-6a.jpg'> Deduce the relationship for an ideal gas . 20
Derive Bragg s e q uation and show that M 2dsin 0 fo r the reflection of X-ray s fr om the fa ces of a crystal.
Cal culate th e in terpl anar spacing spacing) in a cub ic crystal if the second-ord erreflections from such planes are obtained . sin 0 0 · whe n X-rays of A 154 pm are used. 20
D1scu ss the different types of isom erism exhibited by coordination compound.Give suitable examples. 20

What is Nernst equation? Explain the various terms involved .
Calculate the pote ntial of th e fo llowing cell.Wr te down the cell reaction and indicate the polarities of the electrodes 1 O <img src='./qimages/786-7a2.jpg'>
Find the expres sion for CFSE of d 5 6 and d 7 sy stems in weak and strong octahedral fields in terms of Dq and P airing energy) . 20
What is the effe ct of temperature on the vapour pre ssure of a liquid Derive Clapeyron-Clausius equation fo r the equilib riu m between
liquid vaPour
Give the integrated form of this equation . 15
Write IU PAC names of the following 10
[CoCl(H20)2(NH3)4] Cl2
(PtCl(NH 2 CH3 2 {NH 3
3 J Cl 3
(Fe 6 4
4 ][PtC1 4

Give a sho rt account of S-N compounds . 10
Why are Sf elements important? 5
Distingui sh between chemical cell and concentratio n cell giving examples.5
Derive an expre ssion for the e.m.f. of electrod e concentration cell without transference . 12
For the equilibrium
PCI 5 3 Cl 2
at 298 K c =1·8X10-7 • What is 6G0 for the reaction?
R 8 · 3 14 J K mo1 1 20
Give reasons for the following · 8
4 2 is a square planar while Ni(C 4 is tetrahedral .
6 4-is diamagnetic.while is parrunagnetic.
Low- spin tetrahedral complexes are not known.
(Fe F 6 3 1s colourless, while oF6 3 is coloured.