Q: Question 13Convert ammonia to nitric oxide by catalytic oxidation of ammonia. State all conditions.

Reaction:4NH3+5O2→800°CPt.4NO+6H2O+Δ4\text{NH}_3 + 5\text{O}_2 \xrightarrow[800 \degree \text{C}]{\text{Pt}.} 4\text{NO} + 6\text{H}_2\text{O} + \Delta4NH3+5O2Pt.800°C4NO+6H2O+ΔConditions:Temperature : 800°CCatalyst : Platinum (Pt)

Question 1

Question 13Convert ammonia to nitric oxide by catalytic oxidation of ammonia. State all conditions.

Accepted Answer

Reaction:4NH3+5O2→800°CPt.4NO+6H2O+Δ4	ext{NH}_3 + 5	ext{O}_2 \xrightarrow[800 \degree 	ext{C}]{	ext{Pt}.} 4	ext{NO} + 6	ext{H}_2	ext{O} + \Delta4NH3​+5O2​Pt.800°C​4NO+6H2​O+ΔConditions:Temperature : 800°CCatalyst : Platinum (Pt)

Question 2

Question 17State what an aqueous solution of NH3 is called. State how it is prepared giving reasons.

Accepted Answer

An aqueous solution of NH3 is called Liquor Ammonia.Preparation:By dissolving ammonia gas in water using a funnel arrangement.Reasons:Prevents back suction of water andProvides a large surface area for absorption of ammonia gas.NH3 + H2O ⟶ NH4OH [liquor ammonia]

Question 3

Question 18State why an aq. soln. of NH3(i) turns red litmus blue(ii) is a weak base and a weak electrolyte.

Accepted Answer

(i) The alkaline behaviour of aq. soln. of ammonia [NH4OH] is due to the presence of hydroxyl ions [OH-]. Hence, the aq. soln. of ammonia turns red litmus blue.(ii) The aq. soln. of ammonia [NH4OH] is alkaline. It undergoes partial dissociation in aq. soln. to give hydroxyl ions [OH-] in low concentration. Therefore, it is a weak base and a weak electrolyte.

Question 4

Question 21State a reason why reaction of liquor ammonia with nitric acid is a neutralization reaction.

Accepted Answer

As liquor ammonia is an alkali due to the presence of hydroxyl ions.NH3 + H2O ⟶ NH4OHNH4OH ⇌ NH4+ + OH-1When an acid (nitric acid) and an alkali or base combine completely to form salt and water then the reaction is called a neutralization reaction.NH4OH + HNO3 ⟶ NH4NO3 + H2OHence, the reaction between liquor ammonia and nitric acid is a neutralization reaction.

Question 5

Question 22State why an aqueous solution of ammonia (NH4OH) is used for identifying cations.

Accepted Answer

The precipitate which are hydroxides of metallic radicals vary in :coloursolubility in excess of NH4OHHence, ammonium hydroxide is used in qualitative analysis for identifying positive radicals or cations.

Question 6

Question 23State how NH4OH is used for identifying:Fe2+Fe3+Pb2+Zn2+Cu2+ cations.Give also a balanced equation in each case for a known example.

Accepted Answer

A soln. of Fe2+ ions gives dirty green ppt. which is insoluble in excess of NH4OH.FeSO4 + 2NH4OH ⟶ (NH4)2SO4+ Fe(OH)2 ↓A soln. of Fe3+ ions gives reddish brown ppt. which is insoluble in excess of NH4OHFeCl3 + 3NH4OH ⟶ 3NH4Cl + Fe(OH)3 ↓A soln. of Pb2+ ions gives chalky white ppt. which is insoluble in excess of NH4OHPb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2 ↓A soln. of Zn2+ ions gives gelatinous white ppt. which is soluble in excess of NH4OHZnSO4 + 2NH4OH ⟶ (NH4)2SO4 + Zn(OH)2 ↓Zn(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Zn(NH3)4]SO4 + 4H2OA soln. of Cu2+ ions gives pale blue ppt. which is soluble in excess of NH4OHCuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2 ↓Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O

Question 7

Question 24State why the blue ppt. formed on addition of NH4OH to CuSO4 soln. dissolves to give a deep blue solution with excess of NH4OH. Give an equation for the reaction. State why Zn(OH)2 is soluble in excess of NH4OH.

Accepted Answer

Ammonium hydroxide if first added in small quantity and then in excess to a solution of copper sulphate, a pale blue ppt. of copper hydroxide is formed which dissolves in excess of ammonium hydroxide forming a soluble complex salt.CuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2 ↓Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2OThe pale blue ppt. of copper hydroxide is soluble in excess of a NH4OH, since a soluble complex [Cu(NH3)4]SO4 [tetrammine copper [II] sulphate] is formed.Zinc salt forms a white gelatinous ppt. of Zn(OH)2, which dissolves when excess of ammonium hydroxide is added due to the formation of [Zn(NH3)4]SO4ZnSO4 + 2NH4OH ⟶ (NH4)2SO4 + Zn(OH)2 ↓Zn(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Zn(NH3)4]SO4 + 4H2O

Question 8

Question 25Give balanced equations for the reducing reactions of ammonia with(i) copper (II) oxide,(ii) lead (II) oxide,(iii) chlorine using (a) excess NH3 (b) excess Cl2

Accepted Answer

(i) 2NH3 + 3CuO ⟶ 3Cu + 3H2O + N2 [g](ii) 2NH3 + 3PbO ⟶ 3Pb + 3H2O + N2 [g](iii) (a) 8NH3 [excess] + 3Cl2 ⟶ 6NH4Cl + N2(iii) (b) NH3 + 3Cl2 [excess] ⟶ 3HCl + NCl3

Question 9

Question 26State five tests for ammonia where a colour change is involved.

Accepted Answer

Five tests for ammoniaAmmonia turns —Red litmus solution to blue.Methyl orange solution to yellow.Colourless phenolphthalein solution to pink.Pale blue precipitate of CuSO4 into deep blue coloured solutionColourless Nesseler's reagent to pale brown.

Question 10

Question 28Name an ammonium salt which is a constituent of(a) smelling salts(b) dry cells.Give reasons for the use of the named ammonium salt for the same.

Accepted Answer

(a) Ammonium Carbonate, [(NH4)2CO3] is used as smelling salt. It dissociates evolving pungent ammonia gas and hence is used as a constituent for smelling salts.(NH4)2CO3 ⟶ 2NH3 + CO2 + H2OThe pungent smelling NH3 gas revives a fainted person.(b) Ammonium Chloride (NH4Cl) is used in dry cells. It oxidizes Zn to Zn2+ ions. The electrons so produced constitute the electric current.

Question 11

Question 30State what are chlorofluorocarbons and give their use. Give a reason why they are ozone depleting. State a suitable alternative to chlorofluorocarbons which are non-ozone depleting.

Accepted Answer

Chlorofluorocarbons (CFC’s) are compounds of carbon with chlorine or fluorine. CFC are chemicals which like liquefied ammonia gas are used in refrigeration gas.They enter the atmosphere due to their use as coolants in refrigeration and A/C plants and aerosol sprays and cause ozone depletion in the atmosphere.Chlorofluorocarbons (CFC’s) are decomposed by U.V. rays to give free Cl radicals.CFCl3 ⟶ Cl atomThis Cl atom breaks the ozone layer causing ozone depletion.Cl + O3 [ozone] ⟶ ClO + O2Hence, ozone layer located in the stratosphere above the earth, which prevents harmful U.V. rays from reaching the earth, gets depleted.Suitable alternatives to chlorofluorocarbons which are non-ozone depleting include Hydrochlorofluorocarbons [HCFC]

Question 12

Question 1Preparation of ammoniaAmmoniaComplete and balance the equationsLaboratory preparation[from ammonium salts]   1. Ammonium chloride + alkaliNH4Cl + Ca(OH)2 ⟶ ............... + H2O + ............... [g]2. Ammonium chloride + alkaliNH4Cl + NaOH ⟶ ............... + H2O + ............... [g]3. Ammonium sulphate + alkali(NH4)2SO4 + NaOH ⟶ ............... + H2O + ............... [g]4. Ammonium sulphate + alkali(NH4)2SO4 + Ca(OH)2 ⟶ ............... + H2O + ............... [g]Reactions of ammonia with drying agents   5. Sulphuric acid [conc.]NH3 + H2SO4 ⟶ ...............6. Phosphorus pentaoxideNH3 + P2O5 + H2O ⟶ ...............7. Calcium chlorideNH3 + CaCl2 ⟶ ...............Laboratory preparation[from metal nitrides]   8. Magnesium nitrideMg3N2 + H2O ⟶ ............... + ............... [g]9. Calcium nitrideCa3N2 + H2O ⟶ ............... + ............... [g]10. Aluminium nitrideAlN + H2O ⟶ ............... + ............... [g]Manufacture of ammonia 11. Haber's processN2 + H2 ⇌ ............... + ΔTemperature ...............Pressure ...............Catalyst ...............Promoter ...............Favourable conditions :............... [temperature (high/low)]............... [pressure (high/low)]

Accepted Answer

AmmoniaComplete and balance the equationsLaboratory preparation[from ammonium salts]   1. Ammonium chloride + alkali2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3 [g]2. Ammonium chloride + alkaliNH4Cl + NaOH ⟶ NaCl + H2O + NH3 [g]3. Ammonium sulphate + alkali(NH4)2SO4 + 2NaOH ⟶ Na2SO4 + 2H2O + 2NH3 [g]4. Ammonium sulphate + alkali(NH4)2SO4 + Ca(OH)2 ⟶ CaSO4 + 2H2O + 2NH3 [g]Reactions of ammonia with drying agents   5. Sulphuric acid [conc.]2NH3 + H2SO4 ⟶ (NH4)2SO46. Phosphorus pentaoxide6NH3 + P2O5 + 3H2O ⟶ 2(NH4)3PO47. Calcium chloride8NH3 + CaCl2 ⟶ CaCl2.8NH3Laboratory preparation[from metal nitrides]   8. Magnesium nitrideMg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3 [g]9. Calcium nitrideCa3N2 + 6H2O ⟶ 3Ca(OH)2 + 2NH3 [g]10. Aluminium nitrideAlN + 3H2O ⟶ Al(OH)3 + NH3 [g]Manufacture of ammonia 11. Haber's processN2 + 3H2 ⇌ 2NH3 + ΔTemperature 450-500°CPressure 200-900 atmospheresCatalyst Finely divided iron [Fe]Promoter Molybdenum [Mo]Favourable conditions :low temperaturehigh pressure

Question 13

Question 2Chemical properties of ammoniaAmmoniaComplete and balance the equationsCombustibility 12. Burning of ammonia in oxygenNH3 + O2 ⟶ ............... + ...............13. Catalytic oxidation of ammoniaNH3+O2→800°CPt................+...............+Δ	ext{NH}_3 + 	ext{O}_2 \xrightarrow[800 \degree 	ext{C}]{	ext{Pt.}} ............... + ............... + \DeltaNH3​+O2​Pt.800°C​...............+...............+ΔBasic natureReaction of ammonia gas with   14. Hydrochloric acidNH3 + HCl ⟶ ...............15. Nitric acidNH3 + HNO3 ⟶ ...............16. Sulphuric acidNH3 + H2SO4 ⟶ ...............17. Water [Dissociation of aq. soln.]NH3 + H2O ⟶ ...............[NH4OH ⇌ NH4+ + ............... ]Reaction of ammonia [aq. soln.] with   18. Hydrochloric acidNH4OH + HCl ⟶ ............... + ...............19. Nitric acidNH4OH + HNO3 ⟶ ............... + ...............20. Sulphuric acidNH4OH + H2SO4 ⟶ ............... + ...............Reaction of ammonia [aq. soln.] with metallic salt solutions   21. Iron [II] sulphateFeSO4 + NH4OH ⟶ ............... + ............... ↓22. Iron [III] chlorideFeCl3 + NH4OH ⟶ ............... + ............... ↓23. Lead nitratePb(NO3)2 + NH4OH ⟶ ............... + ............... ↓24. Zinc sulphateZnSO4 + NH4OH ⟶ ............... + ...............↓[Zn(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ ............... + H2O]25. Copper sulphateCuSO4 + NH4OH ⟶ ............... + ............... ↓[Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ ............... + H2O]

Accepted Answer

AmmoniaComplete and balance the equationsCombustibility 12. Burning of ammonia in oxygen4NH3 + 3O2 ⟶ 2N2 + 6H2O13. Catalytic oxidation of ammonia4NH3+5O2→800°CPt.4NO+6H2O+Δ4	ext{NH}_3 + 5	ext{O}_2 \xrightarrow[800 \degree 	ext{C}]{	ext{Pt.}} \bold{4NO} + \bold{6H}_\bold{2}\bold{O} + \Delta4NH3​+5O2​Pt.800°C​4NO+6H2​O+ΔBasic natureReaction of ammonia gas with   14. Hydrochloric acidNH3 + HCl ⟶ NH4Cl15. Nitric acidNH3 + HNO3 ⟶ NH4NO316. Sulphuric acid2NH3 + H2SO4 ⟶ (NH4)2SO417. Water [Dissociation of aq. soln.]NH3 + H2O ⟶ NH4OH[NH4OH ⇌ NH4+ + OH-]Reaction of ammonia [aq. soln.] with   18. Hydrochloric acidNH4OH + HCl ⟶ NH4Cl + H2O19. Nitric acidNH4OH + HNO3 ⟶ NH4NO3 + H2O20. Sulphuric acid2NH4OH + H2SO4 ⟶ (NH4)2SO4 + 2H2OReaction of ammonia [aq. soln.] with metallic salt solutions   21. Iron [II] sulphateFeSO4 + 2NH4OH ⟶ (NH4)2SO4 + Fe(OH)2 ↓22. Iron [III] chlorideFeCl3 + 3NH4OH ⟶ 3NH4Cl + Fe(OH)3 ↓23. Lead nitratePb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2 ↓24. Zinc sulphateZnSO4 + 2NH4OH ⟶ (NH4)2SO4 + Zn(OH)2 ↓[Zn(OH)2] + (NH4)2SO4 + 2NH4OH ⟶ [Zn(NH3)4]SO4 + 4H2O25. Copper sulphateCuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2 + ↓[Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ Cu(NH3)4SO4 + 4H2O]

Question 14

Question 5A gas 'A' reacts with another gas 'B' in the presence of a catalyst to give a colourless gas 'C'. The gas 'C' when comes in contact with air produces a brown gas 'D'. The solution of 'A' in water turns red litmus blue. Explain the observations.

Accepted Answer

As the 'A' turns red litmus blue it is a base. Now the gas 'A' combines with 'B' in presence of Catalyst to give colourless gas Nitrogen monoxide. It reacts with oxygen to give brown gas which is Nitrogen dioxide. The gases are given as :A = NH3B = O2C = NOD = NO24NH3 + 5O2 →800°CPt.\xrightarrow[800 \degree 	ext{C}]{	ext{Pt.}}Pt.800°C​ 4NO↑ + 6H2O + Δ2NO + O2 ⟶ 2NO2 [brown gas]

Question 15

Question 6(a) Name the common refrigerant. How does it deplete ozone layer?(b) What is the alternative of chlorofluorocarbon carbon?(c) State the advantages and disadvantages of using ammonia as refrigerant?

Accepted Answer

(a) The main refrigerants used are Freon chlorofluorocarbons (CFC). They deplete ozone layer and contribute to global warming. The chlorofluorocarbons are decomposed by ultraviolet rays to highly reactive chlorine which is produced in the atomic form.CF2Cl2→UltravioletCF2Cl+Cl[free radical]	ext{CF}_2	ext{Cl}_2 \xrightarrow{	ext{Ultraviolet}} 	ext{CF}_2	ext{Cl} + 	ext{Cl} [	ext{free radical}]CF2​Cl2​Ultraviolet​CF2​Cl+Cl[free radical]The free radical [Cl] reacts with ozone and chlorine monoxide is formed.Cl + O3 [ozone] ⟶ ClO + O2This causes depletion of ozone. Chlorine monoxide further reacts with atomic oxygen and produces more free radicals.ClO + O ⟶ Cl + O2Again this free radical [Cl] destroys ozone, and the process continues thereby giving rise to ozone depletion.(b) Liquid ammonia(c) Advantages of ammonia as refrigerant:Ammonia is environmentally compatible. It does not deplete ozone layer and does not contribute towards global warming.It has superior thermodynamic qualities as result ammonia refrigeration systems use less electricity.Ammonia has a recognizable odour and so leaks are not likely to escape. It being lighter than air goes up in the atmosphere not affecting the life too much on earth.Disadvantages of ammonia as a refrigerant are as follows:It is not compatible with copper, so it cannot be used in any system with copper pipes.It is poisonous in high concentration.

Question 16

Question 11The following questions are based on the preparation of ammonia gas in the laboratory:(a) Explain why ammonium nitrate is not used in the preparation of ammonia.(b) Name the compound normally used as a drying agent during the process.(c) How is ammonia gas collected? Explain why it is not collected over water.

Accepted Answer

(a) As ammonium nitrate is explosive in nature and may itself decompose forming nitrous oxide and water vapour, hence it is not used in the preparation of ammonia.NH4NO3→ΔN2O+2H2O	ext{NH}_4	ext{NO}_3 \xrightarrow\Delta 	ext{N}_2	ext{O} + 	ext{2H}_2	ext{O}NH4​NO3​Δ​N2​O+2H2​O(b) Quick lime [CaO] is used as a drying agent during the process.(c) Downward displacement of air is the method used for the collection of the ammonia gas. As ammonia gas is highly soluble in water, therefore, it is not collected over water.

Question 17

Question 14The diagram given below describes the manufacturing process of a gas.(a) Name the process.(b) Identify A, B and C.(c) State the ratio of A and B(d) Write the equation involved with their respective conditions.(e) How is the product separated from unreacted reactants ?

Accepted Answer

(a) Haber's process(b)    A — Nitrogen    B — Hydrogen    C — Liquid ammonia(c) Ratio of A and B is 1:3(d)Reaction:N2 + 3H2 ⇌ 2NH3 + heatFavorable Conditions:Temperature450-500°CPressureAbove 200 atmCatalystFinely divided ironPromoterTraces of molybdenum or Al2O3(e) Product is separated from unreacted reactants by Liquification. Ammonia is liquified easily as compared to nitrogen and hydrogen.

Question 18

Question 4(a) What do you observe when ammonium hydroxide is added to the aqueous solution of :(i) FeSO4(ii) Iron (III) chloride.(iii) Lead nitrate(iv) Zinc nitrate(b) Write balanced equation for Q.4(a).

Accepted Answer

(i) Dirty green ppt. of ferrous hydroxide is formed which is insoluble in excess of NH4OH.(ii) Reddish brown ppt. of ferric hydroxide is formed which is insoluble in excess of NH4OH.(iii) White ppt. of lead hydroxide is formed which is insoluble in excess of NH4OH.(iv) White gelatinous ppt. of Zinc hydroxide is formed which is soluble in excess of NH4OH.(b) The balanced chemical equations are given as :(i) FeSO4 + 2NH4OH ⟶ (NH4)2SO4 + Fe(OH)2 ↓(ii) FeCl3 + 3NH4OH ⟶ 3NH4Cl + Fe(OH)3 ↓(iii) Pb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2 ↓(iv) Zn(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Zn(OH)2 ↓

Question 19

Question 9State the conditions required for : Catalytic oxidation of ammonia to nitric oxide.

Accepted Answer

Conditions for catalytic oxidation of ammonia to nitric oxide are :Temperature : 800°CCatalyst : Platinum (Pt)4NH3+5O2→800°CPt.4NO+6H2O+Δ4	ext{NH}_3 + 5	ext{O}_2 \xrightarrow[800 \degree 	ext{C}]{	ext{Pt.}} 	ext{4NO} + 	ext{6H}_	ext{2}	ext{O} + \Delta4NH3​+5O2​Pt.800°C​4NO+6H2​O+Δ

Question 20

Question 10Give reasons for the following —(a) Liquid ammonia is used as a refrigerant in ice plants.(b) Aqueous solution of ammonia is used for removing grease stains from woollen clothes.(c) Aqueous solution of ammonia gives a pungent smell.(d) Aqueous solution of ammonia conducts electricity.

Accepted Answer

(a) Liquid ammonia is a clear, colourless liquid under pressure. It evaporates rapidly and produces cooling effect. Moreover, Ammonia is environmentally compatible, has superior thermodynamic properties and its leaks are easily detectable due to its recognizable odour. All these reasons make liquid ammonia a good refrigerant.(b) As aqueous solution of ammonia emulsifies or dissolves fats, grease etc., hence it is used for removing grease stains from woollen clothes.(c) Pungent smell of aqueous solution of ammonia is due to the presence of ammonia, which has strong, pungent choking smell.(d) In aqueous solution, the ammonia molecule combines with a hydrogen atom H+ by sharing the lone pair of electrons of nitrogen atom to form ammonium ion (NH4+). Thus, in water, ammonium hydroxide (NH4OH) dissociates into NH4+ (ammonium ion) and OH- (hydroxide ion) as follows:NH4OH ⟶ NH4+ + OH-Due to this ionisation, aqueous solution of ammonia (NH4OH) conducts electricity.

Study of Compounds — Ammonia

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Unit Test Paper 7B — Ammonia