Qualitative Analysis

Observations after adding aqueous sodium hydroxide

• Cu²⁺ : Blue precipitate formed, insoluble in excess

• Fe²⁺ : Dirty green precipitate, insoluble in excess

• Fe^{3+ :} Reddish brown precipitate is formed, insoluble in excess

• Zn²⁺ : White precipitate formed, soluble in excess

• Al³⁺ : White precipitate formed, soluble in excess

• Ca²⁺: White precipitate formed, insoluble in excess

Observations after adding aqueous ammonia

• Cu²⁺ : Blue precipitate formed, soluble in excess

• Fe²⁺ : Dirty green precipitate, insoluble in excess

• Fe^{3+ :} Reddish brown precipitate is formed, insoluble in excess

• Zn²⁺ : White precipitate formed, soluble in excess

• Al³⁺ : White precipitate formed, insoluble in excess

• Ca²⁺: No precipitate

Test for Anions

• NO_3- : Add dilute sodium hydroxide, then add a piece of aluminium foil, Warm the mixture. → Observations: Bubbles seen, gas turn damp red litmus paper blue.

• CO₃^2-: Add dilute acid.→ Observations: Bubbles seen. Gas turn white precipitate in limewater. Gas produced is carbon dioxide.

• Cl^- : add dilute nitric acid. Add aqueous silver nitrate → White precipitate is formed.

• I^- : Add dilute nitric acid. Add aqueous silver nitrate. → yellow precipitate is formed.

• SO₄^2- :Add dilute nitric acid. Add aqueous barium nitrate. → White precipitate is formed.

Test for gases

• Place a damp red litmus paper into the gas. Gas turns damp red litmus paper blue if ammonia gas is present.

• Hydrogen: Insert lighted splint into the gas. Gas will extinguish lighted splint with a ‘pop’ sound if hydrogen gas is present.

• Oxygen: Insert glowing splint into the gas. gas will relight glowing splint if oxygen gas is present.

• Carbon dioxide: Bubble the gas into the limewater. Gas forms a white precipitate in limewater if carbon dioxide gas is present.

• Sulfur dioxide: Bubble the gas into acidified potassium manganate (VII). Gas will turn purple acidified potassium manganate (VII) colourless if sulfur dioxide gas is present.

• Chlorine: Place a damp blue litmus paper into the gas. Gas will turn damp litmus paper red and eventually bleaches it.