10.Sr_Chem.pdf

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BOARD OF INTERMEDIATE EDUCATION Sr. Inter Chemistry

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

SECTION - ANote: 1. Answer ALL questions.

2. Each question carries TWO Marks.3. All are Very Short Answer type questions. 10 2 = 20

1. Calculate the mole fraction of ethylene glycol (C2H6O2) in a solution containing 20% of C2H6O2 by mass.2. Give two examples for "Zero Order reactions".3. Give one use each of a) Cast Iron b) Wrought Iron c) Nickel Steel d) Stainless Steel.4. How do you account for the inert character of N2?5. What are "Interhalogen Compounds"? Give 2 examples.6. How many moles of AgCl are precipitated when 1 mole of CoCl3 . 4 NH3 reacts with excess of AgNO3? Give

primary valency and secondary valency of this complex compound.7. Give the structures and IUPAC names of monohydric phenols of molecular formula, C7H8O.8. Give the equations for the prepration of Phenol from Cumene.9. What are "analgesics"? Give one example each for each class.10. What is "tincture of iodine"? Give its use.

SECTION - BNote: 1. Answer any SIX questions.

2. Each question carries FOUR Marks.3. All are Short Answer Type Questions. 6 4 = 24

11. Explain a) Paramagnetism b) Ferromagnetism c) Ferrimagnetism d) Antiferromagnetism12. Define "Osmotic Pressure". What would be the concentration of glucose solution, if the osmotic pressure is 1.52

bar at 300 K (R = 0.083 L bar Mol-1 K-1)13. Explain the following:

a) Sandmeyer reaction b) Gatterman Reaction14. Write down the Chemical reactions taking place in different zones in the blast furnace during the extraction of

Iron.15. What are "emulsions"? How are they classified? Give one example for each class.16. What is "Lanthanoid Contraction"? What are the consequences of it?17. Give the sources of the following Vitamins and name the diseases caused by their deficiency.

a) A b) D c) E d) K18. (a) What are "elastomars"? Give an example.

(b) What is "Poly Dispersity Index" (PDI)?SECTION - C

Note: 1. Answer any TWO questions.2. Each question carries EIGHT Marks.3. All are Long Answer Type Questions. 2 8 = 16

19. a) What is "electrolysis"? State Faraday's 2nd law of electrolysis.b) Derive an integrated rate equation for a first order reaction.

20. a) How is Ozone prepared? How does it react with the following?i) PbS ii) KI and iii) Hgb) Explain the structures of XeF6 & XeOF4.

21. a) Halo alkanes react with KCN to form alkyl Cyanides as main product while AgCN forms isocyanides as theChief product. Explain.

aq. KOH A

b) C2H5Br What are A and B in the reaction? Balc. KOH

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ANSWERSSECTION - A

1. Calculate the mole fraction of ethylene glycol (C2H6O2) in a solution containing 20% of C2H6O2 by mass.wt. of glycol 20

Ans: nglycol = = = 0.322G.M. wt. of glycol 62wt. of Water 80

nH2O = = = 4.444G.M. wt. of water 18nglycol 0.322 0.322

Xglycol = = = = 0.068nglycol + nH2O 0.322 + 4.444 4.766XH2O = 1 - 0.068 = 0.932

2. Give two examples of "Zero Order Reactions".

PtA: 2 NH3(g) N2(g) + 3 H2(g)1130 K

Au 2 HI (g) H2(g) + I2(s)

3. Give one use each of a) Cast Iron b) Wrought Iron c) Nickel Steel d) Stainless SteelA: a) Cast Iron: Casting Stoves, Railway sleepers.

b) Wrought Iron: Anchors, bolts.c) Nickel Steel: Pendulum, measuring tapes.d) Stainless Steel: Cycles, Utensils.

4. How do you account for the inert character of N2?

A: The bond disassociation of triple bond (N N) is very high i.e. 941.4 KJ/mole. It is not available at room temperature, so it is very difficult to break the bond. Hence it is unable to take part in bond formation, i.e. inert.

5. What are "Inter halogen compounds"? Give 2 examples.

A: The binary compounds formed by two different halogens.

e.g.: ClF3, BrF56. How many moles of AgCl are precipitated when 1 mole of CoCl3 . 4 NH3 reacts with excess of AgNO3?

Give primary valency and secondary valency of this complex compound.

A: Compound is: [Co(NH3)4Cl2] Cl No. of moles of AgCl = Ag+ + Cl

-

= 1 AgCl = 1 Mole

Primary Valency = Oxi. State of Co3 = 3

Secondary Valency = Coordination number of Co = 6

7. Give the Structures and IUPAC names of monohydric phenol of molecular formula, C7H8O.

CH3 CH3 CH3

A: OH

o - Cresol m - cresolOH

OHp - cresol

IUPAC names of:

o - Cresol = 2 - methyl phenol

m - Cresol = 3 - methyl phenol

p - Cresol = 4 - methyl phenol



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8. Give the equations for the prepartion of phenol from Cumene.

CH3 CH3 A: HCCH3 HOOCCH3 OH

O2 H+

+ CH3COCH3H2OCumene Phenol

9. What are ''analgesics"? Give one exmaple for each class.A: Drug which can reduce or abolish pain without causing disturbances of nervous system are called analgesics.

Non - norcotic analgesics : AnalginNorcotic analgesics : Heroin

10. What is "tincutre of iodine" ? Give its use.A: 2 to 3% solution of iodine in alcohol is called tincture of iodine.

Use: Used as an antiseptic.

SECTION - B

11. Explain

a) Paramagnetism b) Ferromagnetism c) Ferrimagnetism d) AntiferromagnetismA: a) Paramagnetism: The phenomenon in which substances are weakly attracted by magnetic field.

e.g.: Fe+3, Cr+3

b) Ferromagnetism: The phenomenon in which substances are strongly attracted by magnetic field. e.g.: Fe, Co

c) Ferrimagnetism: The phenomenon in which substances are weakly attracted by magnetic field than that ofFerromagnetic substances (due to unequal number of parallel & Anti - parallel alignment ofmagnetic domains). e.g.: Fe3O4, NiFe2O4

d) Antiferromagnetism: The phenomenon in which magnetic property cancels as the domains are oppositelyoriented. e.g.: MnO

12. Define osmotic pressure. What would be the concentration of glucose solution, if the osmotic pressure is 1.52 barat 300 K (R = 0.083 L bar mol-1 K-1)

A: Osmotic Pressure: The pressure which is used to be applied on the solution in order to prevent the flow of solvent through semi permeable membrane.

= CRT C = = 1.52/0.083 300 = 0.06 mol L-1

RT

13. Explain the following. a) Sandmeyer reaction b) Gatterman reaction.A: a) Sandmeyer reaction: The rection in which diazonium group of diazonium salt is replaced by the nucleophiles

like Cl- or Br- or CN- in presence of Cu+ ion & corresponding halogen acid.Cu2Cl2/ HCl ArCl + N2 Where R = C6H5 orCu2Br2/HBrArN2X ArBr + N2CuCN/KCN ArCN + N2

b) Gatterman reaction: The reaction in which diazomium group of diazonium salt is replaced by the nucleophiles like Cl-, Br- in presence of Cu powder & corresponding hologen acid.

Cu/HCl ArCl + N2 + CuX

ArN2X Cu/HBr ArBr + N2 + CuX



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14. Write down the chemical reactions taking place in different zones in the blast furnace during the extraction ofiron.

A: A mixture of oxide ore of Iron, lime stone, coke is introduced from the top of blast furnace. Temperature of thefurnace at the bottom is 2200 K. The reactions in different zones.

Low temperature range (500 K - 800 K): Reduction Zone (823 K): Iron oxide is reduced to sponge Iron.

3 Fe2O3 + CO 2 Fe3O4 + CO2Fe3O4 + 4 CO 3 Fe + 4 CO2Fe2O3 + CO 2 FeO + CO2

High Temperature range (900 K - 1500 K): Slag formation zone (1123 K)

1123 KCaCO3 CaO + CO2CaO + SiO2 CaSiO3 (Slag)

Heat absorption Zone (1423 K):C + CO2 2 CO

Fusion Zone (1423 K - 1673 K).Where sponge iron is fused. S, P, Si, Mn, C impurities are present

FeO + CO Fe (fused) + CO2 Reduction Zone (2170 K):

C + O2 CO2C + CO2 2 CO

15. What are "emulsions"? How are they classified? Give one example for each class.

A: Emulsion: The colloidal system in which both the dispersed phase and dispersion medium are in liquid state.

Oil in Water type emulsion:

Dispersed phase: Oil

Dispersion Medium: Water

e.g.: Milk, Vanishing cream.

Water in Oil type emulsion:

Dispersed phase: Water

Dispersion Medium: Oil

e.g.: Butter, Cold Cream.

16. What is "Lanthanoid Contraction"? What are the consequences of it?

A: The phenomenon of gradual decrease of atomic and ionic radii of 14 Lanthanide elements due to diffused shapeof f-orbital and poor shielding effect is called Lanthanoid Contraction.

Consequences: Similar properties of 4d & 5d elements.

It is difficult to separate individual lanthanide elements from their mixture due to similarchemical properties and crystal structure.



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17. Give the sources of the following Vitamins and name the diseases caused by their deficiency.

a) A b) D c) E d) KA:

S.No. Name of the Sources Diseases caused due to deficiencyVitamin

1. A Carrot, Butter, Papaya Night blindness, Xeropthalmia

2. D fish, exposture to sun light Rickets, softening of bones

3. E Sunflower Oil, Sprouted Muscular Weakness increased fragility of RedWheat Germ Oil Blood Cells.

4. K Green Leafy Vegetables delay of blood clotting time.

18. a) What are elastomers? Give an example.b) What is Polydispersity Index (PDI)?

A: a) Elastomers: Polymers which can be stretched on applying force (due to cross links) and returns to its normalshape and size on removal of the force.

e.g.: Buna - N, Buna - S

b) PDI: The ratio of weight average, molecular weight (Mw) to number average molecular weight (

Mn).

MwPDI =

MnSECTION - C

19. a) What is electrolysis? State Faraday's 2nd law of electrolysis.b) Derive an intgegrated rate equation for a first order reaction.

A: a) Electrolysis: The process of decompositon of an electrolyte when electricity is passed through its molten stateor aqueous state.

e.g.: Aqueous K2SO4 on electrolysis gives H2 at cathode and O2 at anode.

Faraday's 2nd law: The amounts of substances deposited or dissolved or liberated at electrodes, when electrolytic cellsare connected in series and same current is passed through them, are proportional to their chemicalequivalents.

W1 E1 =

W2 E2b) First Order reaction: The reactions in which the rate is proportional to the concentration of only one reactant.

A productsRate A

Rate = K[A] where K = rate constantlet 'a' be initial concetnration of A in moles per litre and (a - x) is the concentration of A after 't' seconds

dxRate = = K (a - x)dt

dx = K.dt(a - x)On integrating both sides

dx = K dt(a - x)



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ln (a - x) = Kt + C ............. (1)Where C = integration constant

at t = 0, x = 0

ln a = c ................... (2)Substituting (2) in (1)ln (a - x) = Kt - ln a

aln = Kt(a - x)

1 aK = ln ()t a - x

2.303 aK = log ()t a - xThis is the integrated rate equation for first order reaction.

20. a) How is Ozone prepared? How does it react with the following?i) PbS ii) KI and iii) Hgb) Explain the structures of XeF6 & XeOF4

A: a) O3By passing silent electric discharge through pure, dry, cold Oxygen 10% Ozone is formed.

silent 3 O2 2 O3 H = + 142 K.J./Molelectric discharge

Reactions:i) O3 oxidises black PbS to white PbSO4

PbS + 4 O3 PbSO4 + 4 O2ii) O3 oxidises moist KI to I2

2 KI + H2O + O3 I2 + O2 + 2 KOHiii) Hg loses lustre and meniscus and sticks to glass surface when reacts with O3. This phenomenon is called

"tailing of mercury".

2 Hg + O3 Hg2O + O2b) XeF6

Xe = 5s2 5px1 5py1 5pz1 5d1 5d1 5d1 (3rd excited state)Xe undergoes sp3d3 hybridization. Due to presence of six bond pairs

and one lone pairs. The shape of XeF6 is distorted Octahedral.

XeOF4

5s2 5px1 5py1 5pz1 5d1 5d11 5d1 (3rd excited state)Xe = Hybridization bond

One electron of 5d take part in bond formation.

Xe undergoes sp3d2 hybridization.

Due to presence of one lone pair and 6 bond pairs (Out of 6, one b.p. forms bond, theshape of XeOF4 is square pyramidal.



Xe

F F

FF

F

F

..

F F

F F

O

Xe

..

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21. a) Halo alkanes react with KCN to form alkyl cyanides as main product while AgCN forms isocyanides as ChiefProduct. Explain.

A: KCN ionise to give K+ and CN- ions. Where CN- ion is ambident nucleophile, SO C & N both can donate electrons. As C - C bond is more stable than that of C - N bond, the attack occurs mainly through carbon atom.So C2H5CN will be formed.

C2H5Br + KCN C2H5CN + KBr.AgCN is covalent, so N is free to donate electron pair to form isocyanide as Chief product.

C2H5Br + AgCN C2H5CN + AgBraq. KOH A

b) C2H5Br Balc. KOH

C2H5 Br + aq.K OH C2H5OH + KBr Ethanol

K OH

Br H alC.KOH

H C C H C2H4 + H2O + K Br

H H Ethene

A is Ethanol, B is Ethene.-A.N.S.Sankara Rao

Senior Lecturer in Chemistry



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10.Sr_Chem.pdf