Solubility Rules

Rule 1

Compounds containing NH₄¹⁺ and group 1A metal ions are soluble.

Rule 2

Compounds containing NO₃^1–, ClO₄^1–, and C₂H₃O₂^1– are soluble.

Rule 3

Compounds containing Cl^1–, Br^1–, and I^1– are soluble except those of Ag¹⁺, Tl¹⁺, Hg₂²⁺, and Pb²⁺.

Rule 4

Compounds containing SO₄^2– are soluble except those of Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺.

Rule 5

Most other ionic compounds are insoluble in water.