AP Chem solubility rules and polyatomic ions

Alkali Metal Ions

Always Soluble

NH4+

Always Soluble

NO3-

Always Soluble

ClO3-

Always Soluble

ClO4-

Always Soluble

C2H3O2-

Always Soluble

Cl-

Soluble except Ag+, Pb2+, Hg2^2+

Br-

Soluble except Ag+, Pb2+, Hg2^2+

I-

Soluble except Ag+, Pb2+, Hg2^2+

F-

Soluble except Ca2+, Sr2+, Ba2+, Pb2+

SO4^2-

Soluble except Ca2+, Sr2+, Ba2+, Pb2+

O2-

Insoluble except NH4+ and alkali metals Ca2+, Sr2+, Ba2+

OH-

Insoluble except NH4+ and alkali metals Ca2+, Sr2+, Ba2+

CO3^2-

Insoluble except alkali metals and NH4+

PO4^3-

Insoluble except alkali metals and NH4+

S2-

Insoluble except alkali metals and NH4+

SO3^2-

Insoluble except alkali metals and NH4+

ammonium

NH₄⁺

acetate

C₂H₃O₂⁻

bromate

BrO₃⁻

chlorate

ClO₃⁻

chlorite

ClO₂⁻

cyanide

CN⁻

dihydrogen phosphate

H₂PO₄⁻

hypochlorite

ClO⁻

hydrogen carbonate (bicarbonate)

HCO₃⁻

hydrogen sulfate (bisulfate)

HSO₄⁻

hydrogen sulfite (bisulfite)

HSO₃⁻

hydroxide

OH⁻

iodate

IO₃⁻

nitrate

NO₃⁻

nitrite

NO₂⁻

perchlorate

ClO₄⁻

permanganate

MnO₄⁻

thiocyanate

SCN⁻

carbonate

CO₃²⁻

chromate

CrO₄²⁻

dichromate

Cr₂O₇²⁻

oxalate

C₂O₄²⁻

selenate

SeO₄²⁻

silicate

SiO₃²⁻

sulfate

SO₄²⁻

sulfite

SO₃²⁻

phosphate

PO₄³⁻

phosphite

PO₃³⁻