These are the general rules for assessing solubilities in aqueous solution:
#"All the salts of the alkali metals and ammonium are soluble."#
#"All nitrates, and perchlorates are soluble."#
#"All halides are soluble EXCEPT for"# #
AgX, Hg_2X_2, PbX_2"#.
#"All sulfates are soluble EXCEPT for"# #PbSO_4, BaSO_4, HgSO_4#.
#"All carbonates and hydroxides are insoluble."#
#"All sulfides are insoluble."#
The given rules follow a hierarchy. Alkali metal and ammonium salts tend to be soluble in all circumstances. The one exception to this rule is #K^(+)""^(-)BPh_4# and #NH_4^(+)""^(-)BPh_4#, both of which are as soluble as bricks. #Na^(+)""^(-)BPh_4# is sold as #"kalignost"#, i.e. #"potassium recognizer."#
Of course, we refer to aqueous solution.
