Solubility of Salts and Hydroxides in Water

In the study of inorganic chemistry, especially qualitative analysis, it is useful to know the approximate solubility of common substances. The simple rules of solubility are given below. These rules apply to compounds of the common cations Na, K, Mg , Ca, Ba ,  

All chlorides, bromides, and iodides are soluble except those of silver, mercurous mercury (mercury with oxidation number +1), and lead. PbCl2 and PbBrz are sparingly soluble in cold water (1 g per 100 ml at 20°C) and more soluble in hot water (3 g, 5 g, respectively, per 100 ml at 100°C). 

All sulfates are soluble except those of barium, strontium, and lead. CaSOj, Ag2S04, and Hg2S04 (mercurous sulfate) are sparingly soluble. 

All salts of sodium, potassium, and ammonium are soluble except NaSb(OH)fi (sodium antimonate), KjPtCle (potassium hexachloroplati-nate), (NH4)2PtCl , K3Co(N02)e (NH4)3Co(NO. ), , and KCIO4. 

All hydroxides are insoluble except those of the alkali metals, ammonium, and barium. Ca(OH)2 and Sr(OH)2 are sparingly soluble. 

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