IGNOU BCHCT-133 December 2024 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—A (Marks : 25) (Chemical Energetics and Equilibria) Note: Attempt any five questions from Question Nos. 1 to 7.

Q2.(a) Define state and path functions. Give an example of each. 2

(b) Calculate the amount of heat energy required to raise the temperature of 100 g of copper from 20°C to 70°C. Specific heat capacity of copper is 390 J kg"! K-!.

Q3.(a) Derive a_ relationship between the temperature and pressure for an adiabatic process using the following expression: 2 TV’ = constant

(b) The enthalpies of combustion of methane, graphite and hydrogen at 298 K are — 890.3 kJ mol}, — 393.5 kJ mol! and — 285.8 kJ mol! respectively. Calculate the enthalpy of formation of CH

(g).

Q4.(a) Derive the relationship between the A,U and A,H for reactions involving gaseous reactants and products. 3

(b) Write the equilibrium constant (Kp) expression for the following equilibrium reactions :

Q5.Hy

(g)+1,

(g)0 2HI

(g)

(ii) 4NH3

(g)+50,

(g)0 + 4NO

(g) + 6H,O

(g)

Q6.(a) Crystallisation of a supersaturated solution of sodium acetate is spontaneous and exothermic process. Is the process ‘entropy driven’ or ‘enthalpy driven’ ? Justify your answer. 3

(b) At a pressure of 1 bar, water undergoes fusion at 273.1 K. Calculate the entropy of fusion of water if the molar enthalpy of fusion of water is found to be 6.02 kJ mol!.

Q7.(a) When will the AG° be equal to zero for an equilibrium reaction occurring at room temperature ? 2

(b) For the equilibrium reaction :

Q8.(8)+ 02

(8) / 260:

(8) +196'छ7 predict the direction of shift of equilibrium for the following : 3

(0) removal of 503 Gi) addition of O2

(iii) decrease in temperature

Q9.(a) How would the degree of ionisation of a weak acid change with dilution of its solution ? Explain. 3

(b) Calculate the pH of a buffer solution containing 0.1 M acetic acid and 0.5 M sodium acetate. 2 Given : pKa (acetic acid) = 4.74; log 5 = 0.6990.

Q10.(a) Write the solubility product expressions for the following : 2

(6) PbCle Gi) AL(OH)s

(b) An aqueous solution contains Ba”* and Sr* ions at a concentration of 10-5 M and 10-1 M respectively. Which of the ions would precipitate first on adding a solution of potassium chromate dropwise to the mixture ? Assume that there is no dilution. [Given : K,,(BaCrO,) =1.2x10-" and K,,(SrCrO,) =3.5x10™ at 298 K] Part—B (Marks : 25) (Functional Group Organic Chemistry—I) Note: Attempt any five questions from Question Nos. 8 to 14.

Q11.(a) Which of the following are aromatic and why ? 3

(b) Why do tert. alcohols undergo Sy! reaction ?

Q12.(a) Complete the following reactions and give their specific names :

Q13.RCOR+HCN— > Gi) +CH,cH,coc.!Cs_, ii) | Lope >100°C

(b) How will you convert CH3CH = CH, to the following : 2 @) 1-propanol Gi) 2-propanol

Q14.(a) How is starch converted into ethanol ? Name all the enzymes for this conversion.

(b) What is picric acid ? How is it prepared from chlorobenzene ?

Q15.(a) What are crown ethers ? Give one of their important uses. 2

(b) How is benzaldehyde prepared from the following ? 2

(6) Ce6HsCOCl Gi) CeHsCN

(c) Give one distinguishing lab. test between CeHsCHO and CeHsCOCHs.

Q16.(a) Arrange the following in an increasing order of reactivity towards electrophilic substition reaction. Explain your answer :

(b) Write the products formed in reaction of CHsMgCl with the following : 2

(0) CHsCN Gi) HCHO

Q17.(a) Write two important _ esterification reactions of glycerol. 2

(b) Write the preparation of phenolphthalein and describe its use as an acid-base indicator.

Q18.(a) Why are phenols acidic in nature ? Which of the following will be a stronger acid? 2

(b) What is the type of hybridisation of starred carbon in each of the following ? 3

(i) CH3;CH,Cl Gi) CH, =CHCl

(iii) — 890.3 kJ mol}, — 393.5 kJ mol! तथा

Q19.Hy,

(g)+1,

(g)0 2HI

(g) Gi) 4NH,

(g)+50,

(g)0 4NO

(g)+6H,0@) 2805

(g) + Oo

(g)0 2805

(g) +196kI log 5 = 0.6990.

(i) PbCly

(ii) AIOH)s 298 K W% Kep (BaCrO,) = 1.2 x 10-10 तथा Kep (SrCrO.) = 3.5 x 107] 2? 2 Gi) +CH,cH,coc! “Gs_, Gi oa

(i) Ce6HsCN

(1) CgH,CHO a C,H;COCH, 4 3 & @) CH3CN Gi) HCHO

Q20.CH,CH,Cl Gi) CH, =CHCI

(ii)