Spot Test for Common Anions

Carbonate CO₃²⁻

2H⁺ + CO₃²⁻ → H₂O + CO₂ (g)

Sulfite ion SO₃²⁻

2H⁺ + SO₃²⁻ → H₂O + SO₂

Nitrate ion NO₃⁻

5OH⁻ + 8Al + 2H₂O + 3NO₃⁻ → 8AlO₂⁻ + 3NH₃

Chloride ion Cl⁻

Ag⁺ + Cl⁻ → AgCl

Sulfate ion SO₄²⁻

Ba²⁺ + SO₄²⁻ → BaSO₄ (s)

Acetate ion C₂H₃O₂⁻

C₂H₃O₂⁻ + KI₃ + La(NO₃)

Phosphate ion PO₄³⁻

HPO₄²⁻ + 3NH₄⁺ + 12MoO₄²⁻ + 23H⁺ → (NH₄)₃PO₄∙12MoO³ + 12H₂O

Thiocyanate ion SCN⁻

SCN⁻ + Fe₃⁺ → FeSCN²⁺

Sulfite ion SO₃²⁻

SO₂ gas

Sulfite ion SO₃²⁻

acrid odor gas

Acetate ion C₂H₃O₂⁻

black precipitate

Carbonate CO₃²⁻

carbon dioxide gas

Carbonate CO₃²⁻

colorless & odorless gas

Thiocyanate ion SCN⁻

deep red precipitate

Chloride ion Cl⁻

solid AgCl

Sulfate ion SO₄²⁻

solid BaSO₄

Thiocyanate ion SCN⁻

solid FeSCN²⁺

Phosphate ion PO₄³⁻

solid ammonium phosphomolybdate (NH₄)₃PO₄∙12MoO³

Nitrate ion NO₃⁻

turns red litmus paper → blue

Sulfate ion SO₄²⁻

white precipitate

Chloride ion Cl⁻

white, curdy precipitate

Phosphate ion PO₄³⁻

yellow precipitate