Solubility Rules

Group 1A elements

always soluble

Ammonium (NH₄+)

always soluble

Nitrates (NO₃-)

always soluble

Chlorides (Cl-)

mostly soluble except Ag+, Hg2+, and Pb2+

Bromides (Br-)

mostly soluble except Ag+, Hg2+, and Pb2+

Iodide (I-)

mostly soluble except Ag+, Hg2+, and Pb2+

Sulfates (SO₄^2-)

mostly soluble except Ca, Sr, Ba, and Pb

When are sulfates (SO₄^2-) insoluble?

Ca, Sr, Ba, Pb

Chlorates (ClO₃-)

always soluble

Perchlorates (ClO₄-)

always soluble

Acetate (C₂H₃O₂-)

always soluble

Phosphates (PO₄^3-)

insoluble except NH4+ and Group 1A

Carbonates (CO₃^2-)

insoluble except NH4+ and Group 1A

Chromates (CrO₄-)

insoluble except NH4+ and Group 1A

Hydroxides (OH-)

insoluble except NH4+ and Group 1A

Hydroxides (OH-)

slightly soluble with Sr, Ba, Ca

Oxalates (C₂O₄^2-)

insoluble except NH4+ and Group 1A

Sulfides (S^2-)

insoluble except NH4+ and Group 1

Group 2A except Mg, Ca, and Ba

Sulfides (S^2-) exceptions

Group 2A except Mg, Ca, and Ba

Mnemonic for usually solubles

Nitrates, Acetate, Group 1 Alkalines (NAG)

Sulfates, Ammonium, Group 17 Halides (SAG)

Group 17 Halides

Cl⁻, Br⁻, I⁻

Exceptions to G17

say NAH to PHA (Pb, Hg, Ag)

Exceptions to Sulfates

CaBa SrPb (Senior Peanut Butter)

Mnemonic for insoluble

carbonates, chromates, hydroxides, oxalates, phosphates (CCHOPS)