Solubility Rules

Salts of NH4+ and the alkali metal cations

soluble

Chlorides (Cl-)

soluble except AgCl, Hg2Cl2, PbCl2

Bromides (Br-)

soluble except Ag, Hg, Pb

Iodides (I-)

Soluble except AgI, Hg2I2, HgI2, PbI2

Chlorates (ClO3-, etc.)

always soluble

Perchlorates (ClO4-)

soluble

Nitrates (NO3-) and Nitrites (NO2-)

always soluble

Acetates (CH3COO-)

soluble

Sulfates (SO4 2-)

Soluble except CaSO4, SrSO4, BaSO4, Hg2SO4, HgSO4, PbSO4, and Ag2SO4

Phosphates (PO4 3-)

insoluble except Group 1A and NH4+

Carbonates (CO3 2-)

insoluble except Group 1A and NH4+

metallic oxides (O2-)

insoluble except NH4+ and Group 1A

Metallic Hydroxides (OH-)

insoluble except NH4+ and group 1A and group 2A from calcium down

Sulfides (S2-)

insoluble except Group 1A and NH4+

Sulfites (SO3 2-)

insoluble except Group 1A and NH4+

Chromates (CrO4 2-) (Cr2O7 2-)

AgCl

insoluble

Hg2Cl2

insoluble

PbCl2

insoluble

AgBr

insoluble

Hg2Br2

insoluble

HgBr2

insoluble

PbBr2

insoluble

AgI

insoluble

Hg2I2

insoluble

HgI2

insoluble

PbI2

insoluble

CaSO4

insoluble

SrSO4

insoluble

BaSO4

insoluble

Hg2SO4

insoluble

HgSO4

insoluble

PbSO4

insoluble

Ag2SO4

insoluble

NH4PO4

soluble

NH4CO3

soluble

(Group IA) PO4

soluble

(Group IA) CO3

soluble

(NH4)2O

Soluble

(Group IA) O2-

soluble

NH4OH

soluble

(NH4)2S

soluble

(Group IA or Group IIA from Ca down) OH-

soluble

(Group IA or IIA) S2-

soluble