AP CHEM Solubility Rules

Are all nitrates (NO₃⁻) soluble or insoluble?

Soluble → example: NaNO₃(aq), KNO₃(aq)

Are alkali metal salts (Li⁺, Na⁺, K⁺) soluble or insoluble?

Always soluble → example: KCl(aq), Na₂CO₃(aq)

Are ammonium salts (NH₄⁺) soluble or insoluble?

Soluble → example: NH₄Cl(aq

Are chlorides (Cl⁻), bromides (Br⁻), iodides (I⁻) soluble or insoluble?

Soluble, except with Ag⁺, Pb²⁺, Hg₂²⁺

Are sulfates (SO₄²⁻) soluble or insoluble?

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

Are carbonates (CO₃²⁻), phosphates (PO₄³⁻), sulfides (S²⁻), hydroxides (OH⁻) soluble or insoluble?

Insoluble, except with alkali metals or NH₄⁺

Are metal hydroxides soluble?

Mostly insoluble, except alkali metals and Ba(OH)₂ → example: NaOH(aq) soluble, Fe(OH)₃(s) insoluble

What is a quick trick to remember “always soluble” ions?

NAGS + CaPS → Nitrates, Alkali metals, Group 1, Sulfates Chlorides, Ammonium, Perchlorates, 

What is a quick trick to remember “mostly insoluble” ions?

CO₃²⁻, PO₄³⁻, S²⁻, OH⁻, Ag⁺, Pb²⁺, Hg₂²⁺ → insoluble unless with “always soluble”

How do you identify a precipitate in a reaction?

: Check solubility rules → if product is insoluble, it forms a solid