Anion tests

Carbonate (CO₃²⁻)

Add dilute HCl

• Effervescence (CO₂ gas), turns limewater milky

Sulfate (SO₄²⁻)

Add dilute HCl, then BaCl₂

• White precipitate (BaSO₄)

Sulfite (SO₃²⁻)

Add dilute HCl

• Produces sulphur dioxide (SO₂) gas, turns acidified potassium manganate(VII) from purple to colourless

Halides (Cl⁻, Br⁻, I⁻)

• Add dilute Nitric acid (HNO₃), then silver nitrate (AgNO₃)

• White precipitate (Cl⁻) Chloride

• Cream precipitate (Br⁻),

• Yellow precipitate (I⁻)

Nitrate (NO₃⁻)

Add NaOH + aluminium foil, warm → Produces NH₃ gas, turns damp red litmus paper blue