Solubility Rules for Common Ions and Compounds in Chemistry

Group 1 ions (Li+, Na+, K+, NH4+)

Soluble with no exceptions; always dissolve.

Acetate (C2H3O2−)

Soluble with no exceptions.

Nitrate (NO3−)

Soluble with no exceptions.

Chlorate (ClO3−)

Soluble with no exceptions.

Perchlorate (ClO4−)

Soluble with no exceptions.

Halides (Cl−, Br−, I−)

Soluble except when paired with Ag+, Hg2²+, Hg+, Pb2+, or Cu+.

Sulfide (S2−)

Insoluble except with Ca2+, Sr2+, Ba2+, and all Group 1 ions/NH4+.

Carbonate (CO3²−)

Insoluble except with Group 1 ions or NH4+.

Chromate (CrO4²−)

Insoluble except with Group 1 ions or NH4+.

Phosphate (PO4³−)

Insoluble except with Group 1 ions or NH4+.

Sulfate (SO4²−)

Soluble except with Ca2+, Sr2+, Ba2+, Ag+, and Pb2+.

Hydroxide (OH−)

Insoluble except with Ca2+, Sr2+, Ba2+ (slightly soluble) and fully soluble with Group 1 ions.

NH4OH

NH3 + H2O

H2SO3

H2O + SO2

H2CO3

H2O + CO2

Decomposition: Metal Chlorates

Metal chlorates decompose into a metal chloride + oxygen.

General: MClO₃ → MCl + O₂

Example: 2KClO₃ → 2KCl + 3O₂

Decomposition: Metal Carbonates

Metal carbonates decompose into a metal oxide + carbon dioxide.

General: MCO₃ → MO + CO₂

Example: CaCO₃ → CaO + CO₂

Decomposition: Metal Hydroxide

Metal hydroxides decompose into a metal oxide + water.

General: M(OH)ₙ → MO + H₂O

Example: Cu(OH)₂ → CuO + H₂O

Some acids

Some acids decompose into water + a nonmetal oxide.

General: H₂X Oᵧ → H₂O + X Oᵧ₋₁

Example: H₂CO₃ → H₂O + CO₂

Decomposition: Metal Peroxides

Metal peroxides decompose into a metal oxide + oxygen.

General: MO₂ → MO + O₂

Example: 2BaO₂ → 2BaO + O₂

Higher oxidation number

As, Sn, Fe, Hg, Cu, and Cr,as Stan fell huge cups cracked

Lower oxidation number

Co, Ni, Mn, Pb, Sb, and Bi,