central university of rajasthan … end sem chem.pdfdepartment of chemistry . m.sc-i . ... what is...

CENTRAL UNIVERSITY OF RAJASTHAN DEPARTMENT OF CHEMISTRY

M.Sc-I END-SEMESTER EXAMINATION, 06.12.2010

PAPER: CHT-101 (ANALYTICAL CHEMISTRY) Time allowed: 3 hrs M. Marks: 100

PART-A

Compulsory Question

1. (i) The result of an analysis is 36.97g compared with the accepted value of 37.06g.

What is the relative error in parts per thousand? 3 (ii) How does batch extraction differ from continuous extraction? Explain. 3

(iii) Define distribution coefficient. 3

(iv) What are ion-exchange resins? Name some commonly used ion- exchange

resins in chromatography. 3

(v) Indicate the order in which the following compounds would be eluted from an HPLC column containing reversed phase packing:

Benzene, diethylether, n-hexane 3 (vi) Aniline absorbs at 280 nm (εmax 8600). However in acidic solution the main

absorption band is seen at 203 nm. Explain. 3

(vii) Explain why absorption spectra for atomic species consist of discrete lines at specific wavelengths rather than broad bands for molecular species. 3

(viii) What is paper electrophoresis? Explain. 3

(ix) Discuss the principle of differential thermal analysis. 3

(x) What are the different factors on which thermogravimetric analysis depends? 3

PART-B

Answer any three questions

2. A 50 ml volume of water containing 0.1 g of analyte is to undergo liquid-liquid

extraction by shaking with 25 ml of an organic phase. Analyte is 85 times more soluble in the organic layer than in water. Compare the result of (a) one extraction using all 25 ml of organic phase and (b) three extractions each using 8.33 ml of organic phase. 7½, 7½

3. Following the Woodward –Fieser rules, calculate the absorption maximum for each of the following compounds: 5 × 3

(i)

(ii) (iii)

O (iv) (v)

O

4. Discuss the principle of flame photometry. What are the different components of a flame photometer and what are their uses? 5, 10

5. What is thermogravimetric analysis? What information can be obtained from the pyrolysis curves? Describe the construction of a simple thermobalance. 3, 5, 7

PART-C

Answer any one question

6. (i) A soda ash sample is analysed in the analytical chemistry laboratory by titration with standard hydrochloric acid. The analysis is performed in triplicate with the following results: 93.50, 93.58 and 93.43 % Na2CO3. Within what range are you 95% confident that the true values lies (at 95% confidence level and two degrees of freedom, t = 4.303)? 7 (ii) Discuss in detail the chemical and spectral interferences occurring in atomic absorption spectroscopy. 5, 4

(iii) What are the various classifications of activation analysis? Discuss destructive method of activation analysis. 3, 6

7. (i) Describe two principle solvent extraction systems for metal ions. Give examples of each. 4, 4 (ii) Give the principles of the following types of chromatography: 5 × 2

(a) Paper chromatography (b) Thin layer chromatography (c) Ion-exchange chromatography (d) Affinity chromatography (e) Gel-permeation chromatography

(iii) Write an explanatory note on dropping mercury electrode. 7



PAPER: CHT-102 (CHEMISTRY OF MAIN GROUP ELEMENTS) Time allowed: 3 hrs M. Marks: 100

PART-A

Compulsory Question

1. (i) Write balanced equations for the hydrolysis of XeF2, XeF4 and XeF6

. 3

(ii) Discuss Bent’s rule with example. 3

(iii) Describe the difference in the structure of H3SiN=C=S and H3

CN=C=S. 3

(iv) How does diborane react with ammonia under different experimental conditions? 3

(v) Discuss the role of crown ethers in the extraction of alkali metals. 3

(vi) Describe structure and bonding in borazine. 3

(vii) Give an example of deprotonation reactions of closo-carboranes. 3

(viii) How are the following prepared? 3 (Any Three):

NaOCl, NaClO2, NaClO3, HIO

4

(ix) What structure do you predict for the compounds: B4H10, C2B7H11 and B10H14

2−

? 3

(x) Arrange the following in decreasing order of their reactivity: 3 IF5, ClF3, BrF, IF, ClF, IF7, BrF3, IF3, BrF5

PART-B


2. (i) Draw the Lewis structure for the following molecules and predict the molecular

geometry including expected distortions: 5 × 2 TeCl4, ICl2

+, ClF3, SO2, XeF(ii) Write a short note on atomic inversion in amines and phosphines. 5

4

3. Describe the structures of different types of silicates and give the name and formula of

one example of each type. 15

4. Comment on each of the following observations: 5 × 3 (i) Bond angles for NO2

+, NO2 and NO2− are 180o, 134o and 115o

(ii) Mg, respectively.

2C3 liberates alkyne, CH3

(iii) The chemistry of the fullerenes is dominated by the reactions of C=C bonds. C≡CH on treatment with water.

(iv) Urea is weakly basic in aqueous solution but shows acidic property in liquid ammonia.

(v) Iodine is almost insoluble in water, but it dissolves readily in an aqueous solution of KI.

5. Discuss in detail the chemical properties of the following non-aqueous solvents:

(Any two) 7½, 7½ (i) liquid ammonia (ii) liquid sulphur dioxide. (iii) dimethyl sulfoxide (iv) dimethyl formamide

PART-C


6. (i) Discuss the concept of molecular hydride. Classify and highlight the

characteristic features of various types of molecular hydrides. 3, 6 (ii) Describe the preparation, properties, structure and applications of carbon nano- tubes. 2, 2, 2, 2 (iii) Write an explanatory note on nitrogen activation. 8

7. (i) Consult the Walsh diagram of BeH2

(ii) Write a short note on intercalation compounds of graphite. 7

and predict whether it will be linear or bent. 10

(iii) Describe what happens: 4 × 2

(a) When metallic potassium is dissolved in ammonia to form a dilute solution.

(b) When more potassium is added to form a concentrated solution. (c) When solution (a) and (b) are evaporated carefully in vacuo. (d) When (a) is treated with Fe2O

3



PAPER: CHT-104 (ELECTROCHEMISTRY AND KINETICS) Time allowed: 3 hrs M. Marks: 100

PART-A

Compulsory Question

1. (i) State Rice-Ramsperger-Kassel (RRK) theory. 3

(ii) Put forward distinguishing features of chain reactions. 3

(iii) Why flash photolysis is preferred over relaxation technique? 3

(iv) What are the basic postulates and test of transition state theory? Highlight the

reasons for failure of the transition state theory. 3

(v) A sample of milk kept at 25oC is found to sour 40 times as rapidly as when kept at 4o

C. Estimate the activation energy for the souring process. 3

(vi) Discuss the mechanism of catalyst and co-catalyst action in ionic polymerisation. 3

(vii) Write the cell reactions involved in charging and discharging of batteries. 3

(viii) Identify the chain initiation, propagation and termination steps in H2 and Cl2

combination reaction in presence of oxygen and state the overall expression for the rate of formation of HCl photo-chemically. 3

(ix) Discuss the principle of molecular beam technique. 3 (x) Explain the process and kinetics of corrosion. 3

PART-B


2. a. Discuss in detail the statistical approach to rate theory by Hinselwood. 7

b. What are fuel cells? Explain with suitable examples. 3 c. Calculate the rate constant for the dissociation reaction, CH3CH2Cl CH2=CH2 + HCl at 640K. Given ∆H# = 202 KJ/mol and ∆S#

= -5.5J/K/mol. 5

3. a. Derive the rate law for the complex formation mechanism for I2

formation, assuming validity of steady state hypothesis. 5

b. Suppose initial concentration of iodine atoms is 3.2x10-6M and that of chaperon is 5.9x10-6

M. How long does it take for half of iodine atoms to combine when chaperon is Helium? 5

c. How are different flow techniques helpful in studying kinetics of reactions? 5

4. Discuss the principle of cyclic voltametry. What are the characteristic features of reversible and irreversible cyclic voltametry? 5, 10

5. a. Differentiate kinetics of gas phase and solution phase reactions. 5 b. Evaluate rate constant of diffusion controlled reactions. 5

c. For decomposition reaction of NH4OH NH4

+ + OH- , 0.1 mol/litre of NH4OH is subjected to temperature jump method. The equilibrium constant K=1.8x10-5 and xe = 4.1x10-4 mol/litre . Find k1, k-1

PART-C

and kr 5


6. a. Discuss in detail the kinetics of gas-phase polymerisation of styrene 8

b. State steady state hypothesis and apply it to determine rate constant for

decomposition of ozone. 9

c. What are different theories of corrosion? Recommend methods for the prevention of corrosion 8

7. a. Suggest the role of external impurity in chain termination step for anionic

polymerisation and discuss the kinetics of copolymerisation reactions. 7

b. Explain the structure of double layer by the following models: (any two) 5 x2 i. Gouy Chapmann Model

ii. Stern Model iii. Bockris, Devanathan and Muller Model iv. Helmoltz Model

c. What are composite reactions? How will you derive (k1+k2) for interconversion of α-D glucose to β-D glucose.

8



PAPER: CHT-105 (THERMODYNAMICS) Time allowed: 3 hrs M. Marks: 100

PART-A

Compulsory Question

1) (i) Helium is compressed isothermally and reversibly at 100o

C from a pressure of 2 to 10 bar. Calculate (a) q per mole, (b) w per mole, (c) ∆G, (d)∆H, (e) ∆U, and (f) ∆S , assuming that helium is an ideal gas. 3

(ii) Prove (δV/δT)p = (δS/δP)T

3

(iii) What are excess functions for non-ideal solutions? 3

(iv) Explain the statistical interpretation of entropy. 3

(v) Calculate entropy of mixing of 1 mole of oxygen and 2 moles of hydrogen assuming no reaction occurs and gases behave ideally. 3

(vi) Suggest significance of chemical potential. 3

(vii) Comment on drawbacks of Clausius- Clapeyron equation. 3

(viii) Identify the systems for which it is essential to include the factor of 1/N!

in going from Q to q.

(i) a sample of nitrogen gas (ii) a sample of solid CO (iii) sodium chloride crystals (iv) water vapors 3

(ix) What are thermodynamic potentials and how are they generated? 3 (x) State Raoult’s Law and give limitations of Henry’s law. 3

PART-B Answer any three questions

2) a. Derive ∆S by non-ideal treatment. 5

b. Verify μJT = 1/Cp[T(δV/δT)P

c. Express the variation of activity with temperature and pressure. 5

-V] 5

3) a. Evaluate the effect of temperature on the chemical potential. 5

b. Prove that H = -T2

δT P,N δG/T 5

c. Calculate the change in entropy when 1 mole of helium (ideal gas) is heated from temperature 298K to 1000K at constant pressure, Cv =3/2R 5

4) a. What are partial molar quantities? Discuss the methods for the determination of

partial molar enthalpy and partial molar volume. 5

b. What should be the partial pressure of CO2 gas to achieve 30mg of CO2 gas dissolved in 250ml of water at 25oC? Given that Henry’s Law constant for CO2 gas in water is 1.25x 106 torr at 25o

C. 5

c. Prove ∆G mixing

for an ideal gases = RT∑xlnx 5

5) a. Derive an expression for the translational partition function of a molecule which is free to move in three dimensions. 5

b. A certain atom has 2 fold degenerate ground level, a non degenerate electronically excited level at 3000 cm-1, and a 2-fold degenerate level at 5000cm-1

c. State Stirling’s Approximation. 5

. Calculate the partition function of these electronic states at 2000K. 5

PART-C


6. a. What are Ellingham diagrams? Discuss the effect of temperature and pressure on Gibb’s energy. Show that (δA/δV)T,N = P and (δG/δT)T,N = V

5,5

b. Write short note on regular solution modelc. What is fugacity and discuss methods to determine fugacity. The boiling point of

benzene at 101.3 kPa is 353.2K. Find out the boiling point of benzene at 60 kPa. The enthalpy of vaporisation of benzene at its boiling point is 31.8KJ/mol. 6,4

. 5

7. a. Write an expression for the molecular partition function and explain meaning of each

term involved in it. Show that the molecular partition function gives an indication of the average number of states that are thermally accessible to a molecule at the temperature of the system. 5

b. Derive Gibbs-Duhem Equation. A 10 gm of naphthalene is dissolved in 100g of

benzene at 25o

C.Calculate the chemical potentials of the two components 5x2

c. Explain the positive and negative deviations from Raoult’s law. The vapour pressures of benzene and toluene are 400 and 139 mm Hg, respectively at 60.6o

C Calculate the vapour pressure of a solution consisting of 40.0gm of toluene and 60.0g of benzene. 5x2

Central University of Rajasthan End-Semester Examination, December 2010

Dynamic of Communication Skills and Technical Writing (DCSTW) Department of English (for M.Sc. Chemistry)

DATE: 18-12-2010; TIME: 3 Hrs [MM–100 marks] SECTION I – Short Answer Type Questions; Attempt all the questions.

i. Which method should be adopted for vocabulary building? (3 Marks) ii. You are a new admission in your class. How would you introduce yourself to your

classmates. (3 Marks) iii. Make a list of all the tenses. (3 Marks) iv. Rectify the spelling errors in the following words: (3 Marks)

a. Loughter b. Trustwarthy c. Assamble d. Dissappear e. Revael f. Liberary

v. Fill in the blanks with appropriate forms of verbs. (3 Marks)

a. They_____(try) to help me.

b. I ________never______(see) such a building.

c. He________(run) to catch the ball.

d. A stitch in time______(save) nine.

e. War_______(break) out in Africa.

f. _____you alright?

vi. Identify errors in the following sentences, if there are any, and rewrite them. (2 Marks)

a. Nobody doesn’t care for me. b. How long have you standing here. c. I speak to him last night. d. The train has arrive late night.

vii If you have a headache how would you define it to a doctor? (2 Marks) viii Give two examples of polite requests. (1 Mark)

SECTION II – Long Answer Type Questions. Each question carries 20 marks

II. Write a letter to the editor of The Times of India informing him about the traffic hazards at Kishangarh.

OR Write a letter of advice to your sister informing her about the ways in which she should prepare for her interviews in the corporate sector.

III. Choose a section and answer all questions in that section:

a. How do you define a Group Discussion (GD)? How can an individual lead in a GD? b. Write a paragraph on ‘Modern Trends in Science.’ (300 words) OR a. Write a paragraph on Indian performance in the Asian Games 2010. (200 words) b. Compose a paragraph on Modern Means of Education.

IV Discuss in detail the rural life in Rajasthan. (300 words)

OR a. Discuss in detail the ways of agreeing, disagreeing and presenting an argument in a

group discussion. b. Discuss the effective ways of vocabulary building.

V. Create an imaginary dialogue between a doctor and a patient. (Word limit – 300 words) OR Write a paragraph on ‘The life in a University.’ (Word limit – 300 words)

CENTRAL UNIVERSITY OF RAJASTHANEnd Semester Examination (December 2010)

First Semester M. Sc. Chemistry 2010-11

Subject: CHT 107(Mathematics for Chemists)

Time Allowed: Three Hour Maximum Marks: 100

PART-I

Q.1 Attempt all questions. Each question having 4 marks.

(a) Find the distance between the points P1(3, 4) and P2(4, 6).

(b) Find dydx for y = e2x tan−1x.

(c) Find the derivative of the function (sinx)x.

(d) Given that x = t3 + 3t, y = t3 − 3t, compute d2ydx2 .

(e) Solve the differential equation 2y′′(x) + 6y′(x) + 2y(x) = 0.

(f) Integrate ∫etan−1x

1 + x2dx

(g) Integrate ∫2x

(x− 1)(x+ 3)dx

(h) Evaluate ∫ v2

v1

(nRT

V − nb− n2a

V 2

)dV ; a, b, n,R and Tare constants.

(i) Solved2ψ

dx2+

8 π2mE

h2ψ = 0.

(j) Expand (x+ 5)8.

(k) Find the eleventh term in the expression of (2x+ y2)13.

(l) Fill the blanks

(a+ b)4 = a4 + a3b+ a2b2 + ab3 + b4.

(m) Find general solution of the equation

dy

dx+ 2xy = 2e−x2

.

Q.2 Attempt any five questions. Each question having 8 marks.

(a) The probability of a gas molecule having a speed c laying in a range between c and c+ dc

is given by the Maxwell distribution law for molecular speed:

Pc dc = 4π( m

2πkT

)3/2e−mc2/2kT c2 dc

where m, k and T are constants. Find an expression for most probable speed.1

2

(b) The vibrational potential energy of a diatomic molecule can be approximated by the Morse

function

U(r) = A(1− e−B(r−r0)

)2

where A,B and r0 are constants. Find the value of r for which U is maximum.

(c) The Kirchhoff equation for a chemical reaction relating the variation of ∆H of a reaction

with absolute temperature is [∂(∆H)∂T

]p

= ∆Cp

where ∆Cp is the change in the heat capacity at constant pressure. If ∆Cp is given by

∆Cp = a+ b T + c T 2

drive an equation for ∆H as a function of temperature.

(d) Find the expected value < x > for an electron in the 1st state of Hydrogen atom, given that

< x >= 4(

1a0

)3 ∫ ∞

0e−2r/a0 r3 dr.

(e) In the consecutive reaction A→k1 B →k2 C, where k1 and k2 are rate constants, the

concentration of B, (B), follows the rate equation

d(B)dt

= k1 (A)0 e−k1t − k2(B)

here (A)0 represents the concentration of A at t = 0. Find the concentration (B).

(f) If the fifth term of an arithmetic progression is 10 while 15th term is 40. Write down the

first 5 terms of A. P.

(g)If the sum of first eight terms of an arithmetic progression is 56 and the sum of the first 20

terms is 260. Find the first term and common difference of the A. P.

CENTRAL UNIVERSITY OF RAJASTHAN

DEPARTMENT OF CHEMISTRY

M.Sc. I-SEMESTER EXAMINATION

PAPER: CHP (CHEMISTRY PRACTICAL)

M. Marks: 90

1. Estimate gravimetrically barium ions as barium sulphate in the given solution. 30

2. Separate the given organic mixture by appropriate method and identify individual compounds. 30

3. Study the kinetics of reaction between potassium persulphate and potassium iodide and determine the rate constant when concentration of potassium persulphate and potassium iodide are equal. 30

OR

Study kinetics of methylacetate in presence of mineral acid and evaluate the rate constant.

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