Water Solubility Rules

Flashcards summarizing water solubility rules for common cations, anions, acids, and solubility thresholds.

$$NO_3^-$$

All nitrates are soluble.

$CH_3COO^-$ or $C_2H_3O_2^-$

All acetates are soluble except $AgCH_3COO^*$

$$ClO_3^-$$

All chlorates are soluble.

$$Cl^-$$

All chlorides are soluble except $AgCl$, $Hg_2Cl_2$, and $PbCl_2^*$.

$$Br^-$$

All bromides are soluble except $AgBr$, $Hg_2Br_2$, $HgBr_2^*$, and $PbBr_2^*$

$$I^-$$

All iodides are soluble except $AgI$, $Hg_2I_2$, $HgI_2$, and $PbI_2$.

$$SO_4^{2-}$$

All sulfates are soluble except $Ag_2SO_4^*$, $Hg_2SO_4$, $PbSO_4$, $CaSO_4^*$, $SrSO_4^*$, and $BaSO_4$.

Alkali Metal Cations (Group 1) and $NH_4^+$

All alkali metal cations (Group 1) and $NH_4^+$ salts are soluble.

$$H^+$$

All common inorganic acids and low molecular mass organic acids are soluble.

$$CO_3^{2-}$$

All carbonates are insoluble except those of the IA elements and $NH_4^+$.

$$CrO_4^{2-}$$

All chromates are insoluble except those of the IA elements and $NH_4^+$ ions, as well as $CaCrO_4^*$ and $SrCrO_4^*$.

$$OH^-$$

All hydroxides are insoluble except those of the IA elements, $NH_4^+$, $Ba(OH)_2$, $Sr(OH)_2^*$, and $Ca(OH)_2^*$.

$$PO_4^{3-}$$

All phosphates are insoluble except those of the IA elements and $NH_4^+$.

$$SO_3^{2-}$$

All sulfites are insoluble except those of the IA elements and $NH_4^+$.

$$S^{2-}$$

All sulfides are insoluble except those of the IA and IIA elements and $NH_4^+$.