Insoluble Ionic Compounds

Precipitate reactions

CO₃^2-

Carbonate ion — polyatomic ion carrying -2 charge — forms insoluble compound with group 1 cations & NH₄⁺

CrO₄^2-

Chromate ion — polyatomic ion with a -2 charge — forms insoluble compound with group 1 cations & NH₄⁺

PO₄^3-

Phosphate ion — polyatomic ion carrying a -3 charge — forms insoluble compounds with group 1 cations & NH₄⁺.

S^2-

Sulfide ion — polyatomic ion carrying a -2 charge — forms insoluble compounds with group 1 cations & NH₄⁺.

OH^-

Hydroxide ion — polyatomic ion with a -1 charge — forms insoluble compounds with group 1 cations & Ba²⁺