Carbonates (CO₃^2-) react with dilute acids to form carbon dioxide.

CO₃²- + 2H⁺ → CO₂ + H₂O

Carbon dioxide turns limewater milky.

Halide ions (chloride, Cl^-, bromide, Br^-, iodide, I^-) in solution produce precipitates with silver nitrate solution in the presence of dilute nitric acid.

eg NaCl_(aq) + AgNO_3(aq) → AgCl_(s) + NaNO_3(aq)

Silver chloride is white

Silver bromide is cream

Silver iodide is yellow.

Sulfate ions (SO₄^2-) in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid. Ba²⁺_(aq) + SO₄^2-_(aq) → BaSO_4(s)

Nitrate ions (NO₃^-)are reduced by aluminium powder in the presence of sodium hydroxide solution to form ammonia.

Copper carbonate (CuCO₃) decomposes to copper oxide when heated (green to black).

Zinc carbonate (ZnCO₃) decomposes to zinc oxide when heated (white to white (but hot zinc oxide is yellow)).