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