Revision Notes for Uses of Ammonium Hydroxide & Sodium Hydroxide Class 10 Chemistry ICSE

ICSE Revision Notes for Uses of Ammonium Hydroxide and Sodium Hydroxide Class 10 Chemistry

Chapter Name	Uses of Ammonium Hydroxide & Sodium Hydroxide
Topics Covered	Analytical Chemistry Reactions with sodium hydroxide solution Reactions with ammonium hydroxide Amphoteric nature of zinc and aluminium metals, their oxides and hydroxides
Related Study	Selina Chemistry ICSE Solutions for Class 10 Frank ICSE Solutions for Class 9 Chemistry

Analytical Chemistry

In the qualitative analysis of compounds, their colour helps in their identification. The table given below shows some examples of colourless and coloured ions.

Colourless			Coloured
Cation	Symbol	Cation		Symbol	Colour
Ammonium	NH4+	Cupric		Cu2+	Blue
Sodium	Na+	Ferrous		Fe2+	Light Green
Potassium	K+	Ferric		Fe3+	Yellowish-brown
Calcium	Ca+	Nickel		Ni2+	Green
Magnesium	Mg2+	Chromium		Cr3+	Green
Aluminium	Al3+	Manganese		Mn2+	Pink
Lead	Pb2+
Zinc	Zn2+

Chemical reactions of the soluble salt solutions with NaOH and NH₄OH

Some soluble salts (except sodium and potassium) react with sodium hydroxide and ammonium hydroxide to form insoluble precipitates.

Reactions with sodium hydroxide solution

Aqueous ferrous sulphate (green in colour) reacts with NaOH to form iron (II) hydroxide, which is insoluble in alkali. 

FeSO₄ + 2NaOH → Na₂SO₄ + Fe(OH)₂ 

Other such reactions are shown below: 

Reactions with ammonium hydroxide

Aqueous ferrous sulphate (green in colour) reacts with NH₄OH to form iron (II) hydroxide, which is insoluble in excess of ammonium hydroxide.

FeSO₄ + 2NH₄OH → (NH₄)₂SO₄ + Fe(OH)₂

Other such reactions are shown below:

Amphoteric nature of zinc and aluminium metals, their oxides and hydroxides

Amphoteric nature of zinc and aluminium metals: As zinc and aluminium metals displace hydrogen from the acids as well as alkali, therefore, they are amphoteric in nature. 

Zn + H₂SO₄ (dil.) → ZnSO₄ + H₂(g)

2Al + 3H₂SO₄ (dil.) → Al₂(SO₄)₃ + 3H₂ (g)

Amphoteric nature of zinc and aluminium oxides: As the oxides of zinc and aluminium react with acids as well as alkalies to form salt and water, they are amphoteric in nature. 

Zn + H₂SO₄ (dil.) → ZnSO₄ + H₂O

Al₂O₃ + 3H₂SO₄ (dil.) → Al₂(SO₄)₃ + 3H₂O

Amphoteric nature of hydroxides of zinc and aluminium metals: As the hydroxides of zinc and aluminium react with acids as well as alkalies to form salt and water as the only products, therefore, they are amphoteric in nature.

Zn(OH)₂ + H₂SO₄ (dil.) → ZnSO₄ + 2H₂O

2Al(OH)₃ + 3H₂SO₄ (dil.) → Al₂(SO₄)₃ + 6H₂O

Amphoteric nature of lead oxide: As the oxide of lead react both with hydrochloric acid and sodium hydroxide, it is amphoteric in nature.

PbO + 2HCl → PbCl₂ + H₂O

PbO + 2NaOH + H₂O → Na₂[Pb(OH)₄]

Amphoteric nature of lead hydroxide: As the hydroxide of lead react both with hydrochloric acid and sodium hydroxide, it is amphoteric in nature.

Pb(OH)₂ + 2HCl → PbCl₂ + 2H₂O

Pb(OH)₂ + 2NaOH → Na₂[Pb(OH)₄