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Ammonia
Q.1. Ammonia can be obtained adding water to : [select the correct word]
A: Ammonium chloride B: Ammonium nitrate
C: Magnesium nitride D: Magnesium nitrate.
Ans :- C: Magnesium nitride.
Q. 2. Name: An alkaline gas ‘A’ which gives dense white fumes with hydrogen chloride.
Ans : - Ammonia gas.
Q.3. Write the equation for the following reaction: Aluminium nitride and water.
Ans : - AlN + 3H2O → Al(OH)3 + NH3 [g]
Q.4. Copy and complete the following table relating to an important industrial process. Output
refers to the product of the process not the intermediate steps.
Name of
process
Inputs
Haber
process
Hydrogen
+
Catalyst Equation for catalyzed
reaction
Output
Output
Ans : Name of process
Inputs
Catalyst Equation for
catalyzed reaction
Haber process
Hydrogen
+
Fe
N2 + 3H2 ↔ 2NH2+
∆
NH3
Q. 5.
i.
ii.
iii.
iv.
v.
vi.
vii.
Write an equation for solutions of ammonium chloride and sodium hydroxide are heated.
Ammonium salts decompose on heating. What other property do ammonium salts have in
common?
Choose the correct word from the bracket and write a balanced equation for the same :
Heating ammonium chloride with sodium hydroxide produces ______ [ammonia /
nitrogen].
Name [formula is not acceptable] the gas produced on warming ammonium sulphate with
sodium hydroxide solution.
Write the equation for the preparation of NH3 from ammonium chloride and calcium
hydroxide.
Write the equation for the reaction when a mixture of ammonium chloride and slaked lime
is heated.
From the list of substances given – Ammonium sulphate, Lead carbonate, Chlorine,
Copper nitrate, Ferrous sulphate – State : A compound which on heating with sodium
hydroxide produces a gas which forms dense white fumes with hydrogen chloride.
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Ans : i.
ii.
iii.
iv.
v.
vi.
vii.
viii.
ix.
x.
xi.
xii.
xiii.
Q.11.
Δ
NH4Cl + NaOH → NaCl + H2O + NH3.
(a) Ammonium salts liberate ammonia on treatment with alkalies.
(b) All ammonium salts are soluble in water.
Ammonia.
NH4Cl + NaOH → NaCl + H2O + NH3
Ammonia.
Δ
2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3.
Δ
2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3.
Ammonium sulphate.
Q. 9. (i) How soluble is ammonia in water.
(ii) Give two reasons to show that the solution of ammonia in water contains
hydroxide ions.
(iii) Is ammonia more dense or less dense than air.
Ans : - (i) Ammonia is highly soluble in water. 1 vol. of water dissolves 702 vol. of ammonia at 20
ºC and 1 atm. pressure.
(ii) (a) Ammonia turns red litmus solution blue. (b) Ammonia reacts with acids to form salt
and water.
(iii) Ammonia is less dense than air. [V.D. of ammonia = 8.5 while V.D. of air = 14.4].
Q. 10. (i) Write equation for the following:
(a) Burning of ammonia in oxygen
(b) Catlytic oxidation of ammonia.
What do you observe in (a)?
Name the catalyst used in (b).
In the reaction referred to in (b), the catalyst glows red hot. Why? What is the
name of the industrial process
which starts with the reaction referred to in (b).
(ii) From the gases – ammonia, hydrogen chloride, hydrogen sulphide, Sulphur
dioxide – Select the following:
(a) When this gas is bubbled through copper sulphate solution, a deep blue
coloured solution is formed.
(b) This gas burns in oxygen with a green flame.
Ans : - (i) (a) 4NH3 + 3O2 → 2N2 + 6H2O.
Pt
(b) 4NH3 + 5O2 → 4NO + 6H2O + Δ .
800ºC
Observation – Dry ammonia does not burn when passed through ignited tube. When ammonia is
passed through ignited tube with a passage of oxygen, ammonia burns with a greenish yellow
flame forming nitrogen and water.
Catalyst – Catalyst used is Platinum. The catalyst glows since the catalytic oxidation of ammonia
is an exothermic reaction.
The industrial process is known as ‘Ostwald’s Process’ for the manufacture of Nitric Acid.
(ii) (a) When ammonia gas is passed through Copper sulphate solution, pale blue precipitate of
copper hydroxide is formed. On passage of excess ammonia the pale blue precipitate turns into
deep blue coloured solution due to formation of tetra amine copper(II) sulphate.
CuSO4 + 2NH4OH → (NH4)2SO4 + Cu(OH)2 ↓
Cu(OH)2 + (NH4)2SO4 + 2NH4OH → [Cu(NH3)4]SO4 + 4H2O.
(b) Ammonia.
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i.
ii.
iii.
iv.
v.
vi.
Name a simple method you would employ to prepare ammonium salts in your laboratory.
What property of ammonia is demonstrated by the Fountain Experiment. Write the
balanced equation for the reaction between ammonia and sulphuric acid.
Choose the correct word from the brackets for each sentence and write a balanced
equation for the same.
(a) Ammonium chloride is a soluble salt prepared by ______ (precipitation, neutralization).
(b) When ammonium chloride is heated, it undergoes thermal ______ (decomposition /
dissociation).
Name a gas whose solution in water is alkaline.
Name the ion other than ammonium ion formed when ammonia dissolves in water.
Select the correct compound from the list given – Ammonia, Copper oxide, Copper
sulphate, Hydrogen chloride, Hydrogen sulphide, Lead bromide – which matches the
description given below:
Although this compound is not a metal hydroxide, its aqueous solution is alkaline in
nature.
Ans : i.
ii.
iii.
iv.
v.
vi.
Neutralization : - Ammonia in the gaseous form or in aqueous solution [NH4OH] neutralizes acids
forming the respective ammonium salts.
Fountain Experiment demonstrate the high solubility of ammonia gas in water.
2NH3 + H2SO4 → (NH4)2SO4.
(a) neutralization.
NH4OH + HCl → NH4Cl + H2O
(b) dissociation.
Ammonia.
Hydroxyl ion [OH– ]
Ammonia.
Q.12. (i) How would you distinguish between Zn2+ ans Pb2+ using ammonium hydroxide solution.
(ii) State what is observed when excess of ammonia is passed through an aq. solution of
lead nitrate.
Ans.: - (i) Zn2+ with NH4OH gives white precipitate of zinc hydroxide which dissolves in excess of
NH4OH,
ZnCl2 + 2NH4OH → Zn(OH)2 ↓ + 2NH4Cl
Zn(OH)2+ 2NH4OH + 2NH4Cl → Zn(NH3)4Cl4 + 4H2O
Aqueous solution of lead salt do not show any change on treatment with NH 4OH.
(ii) When ammonia is passed through an aq. solution of lead nitrate, chalky white precipitate of lead
hydroxide is formed which is insoluble in excess of ammonia.
Pb(NO3)2 + 2NH4OH → 2NH4NO3 + Pb(OH)2 ↓
Q.13. (i) What are the products formed when ammonia is oxidized with copper oxide.
(ii) From the following gases – ammonia, chlorine, hydrogen chloride, Sulphur dioxide, select
the gas that matches
the description given below:
(a) The gas [B] turns moist red litmus paper blue. What is the name of gas [B]?
(b) Write the equation for the reaction that takes place when gas [B] is passed over heated
CuO.
(iii) Write an equation for the reaction of chlorine with excess of ammonia.
(iv) Write a balanced chemical equation to illustrate the reducing nature of ammonia.
Ans : - (i) Nitrogen, Copper and water.
2NH3 + 3CuO → 3Cu + 3H2O + N2.
(ii) (a) Ammonia.
(b) 3CuO [heated] + 2NH3 → 3Cu + N2 + 3H2O.
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(iii) 8NH3 [excess] + 3Cl2 → 6NH4Cl + N2.
(iv) 3CuO + 2NH3 → 3Cu + N2 + 3H2O.
Q.14. (i) What do you observe when ammonia gas is bubbled through red litmus solution.
(ii) State what you observe when a piece of moist red litmus paper is placed in a gas jar of
ammonia.
Ans : - (i) The red litmus solution becomes blue.
(ii) The red litmus paper turns blue.