Solubility Rules and Common Polyatomic Ions

Vocabulary practice flashcards covering general solubility rules and common polyatomic ions.

Solubility Rule 1 (Nitrates)

Most nitrate ($NO_3^-$) salts are soluble.

Solubility Rule 2 (Alkali Metals & Ammonium)

Most alkali metal (group 1A) salts and $NH_4^+$ are soluble.

Solubility Rule 3 (Halides)

Most $Cl^-$, $Br^-$, and $I^-$ salts are soluble, except for those containing $Ag^+$, $Pb^{2+}$, and $Hg_2^{2+}$.

Solubility Rule 4 (Sulfates)

Most sulfate salts are soluble, except for $BaSO_4$, $PbSO_4$, $Hg_2SO_4$, and $CaSO_4$.

Solubility Rule 5 (Hydroxides)

Most $OH^-$ are only slightly soluble ($NaOH$ and $KOH$ are soluble; $Ba(OH)_2$ and $Ca(OH)_2$ are marginally soluble). Slightly soluble is treated as insoluble and marginally soluble as soluble.

Solubility Rule 6 (Insoluble Salts)

Most $S^{2-}$, $CO_3^{2-}$, $CrO_4^{2-}$, and $PO_4^{3-}$ salts are only slightly soluble, except for those containing alkali metal cations (group 1A) or $NH_4^+$.

Mercury(I)

A polyatomic cation with the chemical formula $Hg_2^{2+}$.

Ammonium

A polyatomic cation with the chemical formula $NH_4^+$.

Nitrite

A polyatomic anion with the chemical formula $NO_2^-$.

Nitrate

A polyatomic anion with the chemical formula $NO_3^-$.

Sulfite

A polyatomic anion with the chemical formula $SO_3^{2-}$.

Sulfate

A polyatomic anion with the chemical formula $SO_4^{2-}$.

Hydrogen sulfate

A polyatomic anion with the chemical formula $HSO_4^-$ (bisulfate is a widely used common name).

Hydroxide

A polyatomic anion with the chemical formula $OH^-$.

Cyanide

A polyatomic anion with the chemical formula $CN^-$.

Phosphate

A polyatomic anion with the chemical formula $PO_4^{3-}$.

Hydrogen phosphate

A polyatomic anion with the chemical formula $HPO_4^{2-}$.

Dihydrogen phosphate

A polyatomic anion with the chemical formula $H_2PO_4^-$.

Thiocyanate

A polyatomic anion with the chemical formula $NCS^-$ or $SCN^-$.

Carbonate

A polyatomic anion with the chemical formula $CO_3^{2-}$.

Hydrogen carbonate

A polyatomic anion with the chemical formula $HCO_3^-$ (bicarbonate is a widely used common name).

Hypochlorite

A polyatomic anion with the chemical formula $ClO^-$ or $OCl^-$.

Chlorite

A polyatomic anion with the chemical formula $ClO_2^-$.

Chlorate

A polyatomic anion with the chemical formula $ClO_3^-$.

Perchlorate

A polyatomic anion with the chemical formula $ClO_4^-$.

Acetate

A polyatomic anion with the chemical formula $C_2H_3O_2^-$.

Permanganate

A polyatomic anion with the chemical formula $MnO_4^-$.

Dichromate

A polyatomic anion with the chemical formula $Cr_2O_7^{2-}$.

Chromate

A polyatomic anion with the chemical formula $CrO_4^{2-}$.

Peroxide

A polyatomic anion with the chemical formula $O_2^{2-}$.

Oxalate

A polyatomic anion with the chemical formula $C_2O_4^{2-}$.

Thiosulfate

A polyatomic anion with the chemical formula $S_2O_3^{2-}$.