IGNOU BCHCT-133 June 2022 Previous Year Question Paper

Q1.Write your Enrolment number, course code and part title clearly on each of the two answer books.

(iii) Marks are indicated against each question. Part—I (Marks : 25) (Chemical Energetics and Equilibria) Note: Attempt any five questions from question nos. 1 to 7.

Q2.(a) What are State Functions ? Give any two examples of thermodynamic properties that are state functions. 2 Define heterogeneous system giving an example.

(b) Calculate the amount of heat required to increase the temperature of 2.00 moles of krypton from a temperature of 100 K to 500 K in: 3 @) an isobaric process, and Gi) an isochoric process Given: C,,,= 1247 JK mol! and Cym = 20.78 JK* mol"!.

Q3.(a) State Hess’ law of constant heat summation and give its significance. 2

(b) Predict the enthalpy change for the following reaction : 3 H H HH H H-C-C-C-Br HH H You may use the following values of bond enthalpies : Bond enthalpy Bond (kJ mol-1) C-C 347 C=C 620 C-H 415.9 C-Br 234 H-Br 366.

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Q4.(a) Give any two statements of the second law of thermodynamics. 2 What is residual entropy ? What kind of systems show residual entropy ?

(b) One mole of an ideal gas taken in a cylinder filled with massless and friction- less piston and occupies a volume of 1 dm? at 400 K. The gas is isothermally and reversibly expanded to five times its initial volume. Calculate the entropy change for the process.

Q5.(a) State Le-Chatelier’s principle. 2 Derive the relation between Kp and Ke for the following reaction : Ss +0, g —SO, g

(b) The change in heat capacity at constant pressure for a reaction is found to be

Q6.7 JK"! mol! and is observed to be independent of temperature. If the value of ArH° at 298 K is — 35.1 kJ mol, calculate the value of Ar H® at 375 K.

Q7.(a) What is standard state Gibbs energy ? What is its significance for an equilibrium reaction ? 2 Write the reaction between NH3 and H20 and identify the conjugate acid-base pairs in it.

(b) Calculate the value of equilibrium constant, Kp for the following reaction at 1000 K:

Q8.g +O, g = 250, g Given : Pgo, = 3.42 x 104Pa Po, = 3-18 x 104Pa and go, = 3.58 x

Q9.(a) Why are the _ successive ionization constants for polyprotic acids smaller and smaller ? 2

(b) Define salt hydrolysis and calculate the degree of hydrolysis of acetate ions in

Q10.01 M aqueous solution of sodium acetate at 298 K. 3 [Given : Ka (CH3sCOOH) = 1.8 x 10° at 298 K] Arrange ammonia, bromamine = and methylamine in increasing order of their basicities giving reasons.

Q11.(a) What would be the nature (acidic/basic/neutral) of an aqueous solution of :

Q12.NH«NO3

(ii) CHs3COONa ? Give reasons (qualitative).

(b) Define solubility product constant and derive an expression for the solubility product constant for a sparingly soluble salt of MA type having a solubility of S mol dm-. 3 Part—II (Marks : 25) (Functional Group Organic Chemistry—I) Note: Attempt any five questions from question nos. 8 to 14.

Q13.(a) What is Wurtz-Fittig reaction ? How would you prepare ethylbenzene from bromobenzene by this reaction ? 2

(b) Complete any three of the following reactions : 3 @ +Zn Zn dust Distillation MgBr Gi) QO + CH,CH,CH,Br —“Y_, ether Gi) OC + CH,CH,C] —“s _, ieee

(iv) O Zn/Hg 25% HCl

Q14.Explain the mechanism of aromatic electrophilic substitution reaction with the help of a suitable example.

Q15.Nitration of phenol gives o-nitrophenol and p-nitrophenol whereas the nitration of nitrobenzene predominantly gives m-dinitrobenzene. Explain.

Q16.(a) What are ortho- and _para-directing deactivators ? Give an example. 2

(b) How can the following conversions be carried out ? Answer any three giving equations : 3 @) Benzene to cyclohexane Gi) Methylbenzene to m-bromobenzoic acid

(ii) Iodobenzene to Biphenyl

(iv) Ethylbenzene to 1-chloro-1- phenylethane

Q17.Give the mechanisms involved in any two of the following reactions : 5

(i) Bromoropane —> propanol

(ii) 2-chloro-2-methylpropane -» 2-methyl-2- propanol

(iii) 2-bromo-2-methylpropane -—» 2-methyl- propene

Q18.Give the chemical equations for any five of the following reactions : 1x5=5 @)_ Pinacol-Pinacolone rearrangement Gi) Schotten Bauman reaction

(ii) Reimer-Tiemann reaction

(iv) Wittig reaction

(v) Aldol condensation

(vi) Claisen-Schmidt reaction

(vii) Mannich reaction

Q19.Complete any five of the following reactions : 1x5=5 CH; 5 _ 6) 8286 हि (@) NaOH/573 K

(ii) CO fj H/H,0 2 wee 0) NaCN Gv) O +Bry CHyCOOH ) O SS Cl Hy/Pd+BaSOq |, 222 CHO wii) CE CHOHIH,O* | TAC, = 12.47 JK mol)! H H HHH oto H-C-C-C-Br oto HHH kJ mol-! C=C 620 C-H 415.9 C-Br 234 H-Br 366.

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Q20.1. 0. Ss +0, g =—=SO, g ArH? @ A -35.1kJ mol है, तो

Q21.g +O, g = 2803 g Pgo, = 3.42 x 104Pa Po, = 3-13 x 104Pa TAM — pg, = 3.58 x 10*Pa =18x10%, 298K™] NHsNO3

(ii) CHsCOONa

Q22.(8) +Zn ES MgBr Gi) QO + CH;CH,CH,Br

(ii) O + CH,CH,C] —ACs_, CHO

(iv) CO 2nlHe 25% HCL (९) tesla WA CH, i

(0) BoH,

Q23.CH; -C = CH, —aio. on 7? ii NaOH/573 K ” O ane iii

(6) NaCN

(iv) QO +Bry CH;COOH v~ Cl w) OC > _ म,04+880,

Q24.1. 0. CHO