03.Sr_Chem

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Board of Intermediate EducationSenior Inter - Chemistry

Model Paper (English Version)Time: 3 Hours Max. Marks: 60

SECTION - A

Note: 1) Very Short Answer type questions.

2) Answer ALL questions. 10 ×× 2 = 20

1. What are "Tetrahedral holes" and "Octahedral holes"?

2. X - rays of wave length equal to 0.134 nm gave a first order diffraction from the

surface of a crystal. The θ value was found to be 10.5°C. Calculate the distance

between the planes in the crystal.

3. Give the composition of "Brass" and "Nichrome".

4. What is "Poly Dispersity Index"?

5. What is "Aspirin"? How it is prepared?

6. What are "Hormones"? Give two examples.

7. Give two biological functions of lipids.

8. What are artificial sweetening agents?

9. What is "Chloropicrin"? How is it formed from CHCl3?

10. Complete the following:

Red P4a) CH3COOH →

Cl2Zn-Hg

b) CH3COCH3 → Conc. HCl

SECTION - B

Note: 1) Short Answer type questions.

2) Answer any SIX questions. 6 ×× 4 = 24

11. Define "Molarity". Calculate Molarity and Normality of a dibasic acid solution

(Mol. wt. = 132) having 33g. of the acid in 400 ml.

12. State Faraday's second law of electrolysis. At 25°C, at infinite dilution, Equiv-

alent Conductance of CH3COONa, HCl and NaCl are 91, 426, 126 ohm−1 cm2

respectively. Calculate Λ°

of CH3COOH.




13. What is "salt hydrolysis"? What is the nature of aqueous solution of sodium

acetate? Give equation.

14. What is Catalysis? How is Catalysis classified? Give an example of each.

15. State Hess law of constant heat summation and give its applications.

16. How is white Bauxite purified by Serpeck's process?

17. a) Give the structure of P4O10.

b) What is Nitrolim? How is it prepared?

18. Give the Werner structures for the following complex compounds

a) CoCl3. 6 NH3 b) CoCl3. 5 NH3

c) CoCl3. 4 NH3 d) CoCl3. 3 NH3

SECTION - C

Note: 1) Long Answer type questions. 2 ×× 8 = 16

2) Answer any TWO of the following.

19. a) How is Cl2 prepared in Nelson Cell?

b) Give the reactions of Ozone with the following:

i) Hg ii) SnCl2 iii) SO2 iv) H2O2

20. State Lechatlier's principle and apply it to the following equilibrium.

N2 (g) + 3 H2 (g) 2 NH3 (g) + Heat energy

21. Write one method of preparation of Nitro Benzene in the laboratory. What are

the products formed when Nitro Benzene undergoes reduction in

i) Acid Medium ii) Alkaline Medium iii) Neutral Medium




ANSWERSSECTION - A

1. What are 'Tetrahedral holes' and 'Octahedral holes'.

Ans: A hole formed between four spheres when they are arranged tetrahedrally are

called 'tetrahedral holes', where as a hole formed between six spheres when they

are arranged octahedrally are called 'octahedral holes'.

2. X-rays of wave length equal to 0.134 nm gave a first order diffraction fromthe surface of a crystal. The θθ value was found to be 10.5°°. Calculate thedistance between the planes in the crystal.

Ans: nλ = 2d sinθ

nλ 1 × 0.134∴ d = = = 0.3677 nm.

2 sin θ 2 × 0.1822

3. Give the composition of 'Brass' and 'Nichrome'.

Ans: Brass: 60 - 80% Cu, 20 - 40% Zn

Nichrome: 60% Ni, 25% Fe, 15% Cr.

4. What is 'Poly Dispersity Index'?

Ans: The ratio of weight average molecular weight ( Mw) and the number average

molecular weight ( Mn) of a polymer.

Mw

P.D.I. = Mn

5. What is 'Aspirin'? How is it prepared?

Ans: Aspirin is acetyl salicylic acid. It can be prepared by acetylation of salicylic

acid with acetic anhydride.

6. What are 'Hormones'? Give two examples.

Ans: Carbon compounds that transfer biological information from one group of cells

to distinct organs in human body are called hormones.

e.g.: Insulin, Testosterone.



CH3COOH →

COOH

OH + CH3CO. O. COCH3

COOH

Aspirin

OCOCH3


7. Give two biological functions of lipids.

Ans: ★ Lipids are energy sources. ★ Lipids are food reserves.

8. What are artificial sweetening agents?

Ans: The chemical substances not only controls the intake of calories but also gives

sweet taste.

e.g.: Sucralose, Saccharin.

9. What is 'Chloropicrin'? How is it formed from CHCl3?

Ans: Nitro Chloroform is is called Chloropicrin. It is formed when CHCl3 reacts with

the vapours of HNO3.

C H Cl3

+ HO − NO2 → CCl3NO2 + H2O

10. Complete the following.

Red P4 Zn −− Hg a) CH3COOH →→ b) CH3COCH3 →→

Cl2 Conc. HCl

Red P4 Red P4Ans: a) CH3COOH → CH2Cl COOH →

+ Cl2 −HCl + Cl2 −HCl

Zn−Hgb) CH3 C O CH3 → CH3CH2CH3 + H2O

H2 H2 Conc. HCl

SECTION - B

11. Define molarity.

Calculate molarity and normality of a dibasic acid solution (Mol. wt. 132)having 33 g. of the acid in 400 ml.

Ans: Number of gram moles of solute present in one litre solution is called molarity (M).

Wt. of solute 1000M = ×

Gram wt. of solute Vol. of solution (ml)

33 1000Molarity (M) = × = 0.625 M

132 400

Wt. of solute 1000Normality (N) = ×

G.Eq. wt. of solute Vol. of solution (ml)

33 1000= × = 1.25 N.

66 400




12. State Faraday's second law of electrolysis. At 25°°C, at infinite dilution,Equivalent Conductance of CH3COONa, HCl and NaCl are 91, 426, 126ohm−−1 cm2 respectively. Calculate ΛΛ

°°of CH3COOH.

Ans: When the same quantity of electricity is passed through different cells

containing fused or aqueous electrolytes, connected in series, the mass of sub-

stances deposited (or dissolved or liberated) at electrodes are in the ratio of their

equivalent weights.

e.g.: mCu : mAg : mH2 = ECu : EAg : E H2

Λ CH3COOH = Λ C2H5COONa + Λ HCl − Λ NaCl

= 91 + 426 − 126

= 391 ohm−1 cm2.

13. What is 'salt hydrolysis'? What is the nature of aqueous solution of Sodiumacetate? Give equation.

Ans: Anion or Cation or both of a salt reacts with water to give OH−

ions or H+

ions

or both is known as salt hydrolysis. The nature of sodium acetate solution is

alkaline, as it under goes anionic hydrolysis.

CH3COO−

+ H2O → CH3COOH + OH−

KwKh =

Ka

14. What is Catalysis? How is Catalysis classified? Give an example of each.

Ans: The phenomenon of changing the rate of a reaction by a substance (without

consuming) is known as Catalysis.

1) Homogeneous catalysis: The catalysis in which the catalyst and the

reactants are in the same phase.

NO (g)

e.g.: 2 SO2 (g) + O2 (g) 2 SO3 (g)

2) Heterogeneous catalysis: The catalysis in which the catalyst and reactants

are in different phases.

Fe (s) e.g.: N2 (g) + 3 H2 (g) 2 NH3 (g)

15. State Hess law of constant heat summation and give its applications.

Ans: The heat of the reaction remains same whether the reaction takes place in a

single step or many steps.




e.g.: C (graphite) + 12

O2 (g) → CO (g); ∆H = −110.5 K.J.

CO (g) + 12

O2 (g) → CO2 (g); ∆H = −283.0 K.J.C (graphite) + O2 (g) → CO2 (g); ∆H = − 393.5 K.J.

Applications: ★ Lattice energy or electron affinity can be calculated.

★ Heat of transformation can be calculated.

16. How is white Bauxite purified by Serpeck's process?

Ans: The powdered white Bauxite (containing SiO2) is mixed with coke and heated

in N2 gas. The reactions occurred are

SiO2 + 2 C → Si ↑ + 2 CO ↑Al2O3 + 3 C + N2 → 2 Al N + 3 CO↑

Al N on hydrolysis gives Al(OH)3

Al N + 3 H2O → Al(OH)3 + NH3

Al(OH)3 is filtered, washed and ignited to get pure Al2O3

1200°C2 Al(OH)3 → Al2O3 + 3 H2O

17. a) Give the structure of P4O10

b) What is Nitrolim? How is it prepared?

Ans: a) Four Oxygen atoms are surrounded by each P atom.

b) The mixture of Calcium Cyanamide and graphite is called Nitrolim. It is

formed when CaC2 reacts with N2 at 1273 − 1373 K.

1273 − 1373 KCaC2 + N2 → CaCN2 + C

(graphite)



O↑P

O O

P P

O

P↓O

O

O O

O ← → O


18. Give the Werner structures for the following complex compounds.

a) CoCl3. 6 NH3 b) CoCl3. 5 NH3

c) CoCl3. 4 NH3 d) CoCl3. 3 NH3

Ans:

SECTION - C19. a) How is Cl2 prepared in Nelson Cell?

b) Give the reactions of Ozone with the following.

i) Hg ii) SnCl2 iii) SO2 iv) H2O2

Ans: a) Nelson Cell consists perforated "U" shaped

steel tube having thin lining of asbestos inside

acts as cathode. Brine solution (aqueous NaCl) is

taken in this steel tube as an electrolyte. A

graphite rod suspended in this solution acts as

anode.

This "U" shaped tube is placed in iron tank.

Steam is passed from bottom to clear pores and keep

the substances hot. On passing electricity, Cl2 is liber-

ated at anode. Na+ ions pass through pores and reacts

with steam to form NaOH & H2.



a) NH3

Cl−

H3N NH3

Co+3

Cl−

H3N NH3

Cl−

NH3

b) Cl−

H3N NH3

Cl− Co+3 Cl−

H3N NH3

NH3

d) Cl−

H3N NH3

Co+3

Cl− Cl−

NH3

c) Cl−

H3N NH3

Co+3 Cl−

H3N NH3

Cl−


Reactions in the cell:

2 NaCl → 2 Na+ + 2 Cl- (Ionization)

At Anode: 2 Cl- → Cl2 + 2 e- (oxidation)

At Cathode: 2 H2O + 2 e- → 2 OH- + H2 (reduction)

2 Na+ + 2 OH- → 2 NaOH

NaOH is collected in catch basin and concentrated further.

b) (i) O3 reacts with Hg to give mercurous oxide.

2 Hg + O3 → Hg2O + O2 (Tailing of mercury)

(ii) Ozone oxidises SnCl2 to SnCl43 SnCl2 + 6 HCl + O3 → 3 SnCl4 + 3 H2O

(iii) Ozone oxidises SO2 to SO3

3 SO2 + O3 → 3 SO3

(iv) O3 reduces H2O2 to H2O

H2O2 + O3 → H2O + 2 O2.

20. State Lechatlier's principle and apply it to the following equilibrium.

N2 (g) + 3 H2 (g) 2 NH3 (g) + Heat energy

Ans: "If a system at equilibrium is disturbed either by change in concentration,

temperature or pressure, then the equilibrium shifts towards the direction in

which that effect nullified or minimised".

Effect of pressure:

Increase of pressure: A high pressure (200 atm) is favoured as equilibrium

shifts in forward direction (from more number of moles side to less number of

moles side) and gives more NH3.

Decrease of pressure: If pressure is decreased, equilibrium shifts in backward

direction, i.e. dissociation of NH3 takes place.

Effect of Temperature:

Increase of Temperature: An optimum temperature 725 - 775 K favours

forward reaction to give more NH3.

Decrease of temperature: It is exothermic reaction, decrease of temperature

favours, but rate of reaction is slow. Practically optimum temperature is used to

get more NH3.

Effect of Concentration:

Addition of N2 & H2: Favours forward reaction, equilibrium shifts in forward

direction to give more NH3.




Removal of N2 & H2: Equilibrium shifts in backward direction, dissociation of

NH3 takes place.

Addition of NH3: Equilibrium shifts in backward direction, dissociation of

NH3 takes place.

Removal of NH3: Favours forward reaction, equilibrium shifts in forward

direction to give more NH3.

Optimum conditions:

Pressure: 200 atm (High pressure)

Temperature: 725 K - 775 K (Optimum temperature)

Concentration: Addition of N2 & H2, removal of NH3

Catalyst: Finely powdered iron.

Promoter: Mo

21. Write one method of preparation of Nitrobenzene in the laboratory. Whatare the products formed when Nitrobenzene undergoes reduction in

i) Acid medium ii) Alkaline medium iii) Neutral medium.

Ans: Preparation: Benzene on Nitration below 60°C gives Nitrobenzene.

Conc. H2SO4C6H5 H + HO NO2 → C6H5NO2 + H2O

< 60°C

Properties:

i) In acid medium, it is reduced to aniline.

NO2 Zn

NH2

O + 6 (H) → O + 2 H2OHCl

ii) In alkaline medium, it is reduced to hydrazo benzene.

ZnO NO2 + 10 (H) + O2 N O → O N − N O + 4 H2O

Alc. KOH H H

iii) In neutral medium, it is reduced to N-phenyl Hydroxyl amine.

NO2 Zn

NHOH

O + 4 (H) → O + H2OHCl

Prepared by A.N.S. Sankara Rao



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03.Sr_Chem