These rules are used only in the Predicting Reaction Section of the AP Exam. We all know that there are no ionic solids that are completely "insoluble" in water.
1.All nitrate compounds (NO31-) are soluble.
2.All acetates (C2H3O21-) are soluble except AgC2H3O2. Acetate can also be represented as CH3COO1-
3. All chlorates (ClO31-) are soluble.
4. All alkali metal cations (Group 1) and ammonia (NH41+) are soluble.
5. All bromides (Br1-), chlorides (Cl1-), and iodides (I1-) are soluble except:
6. All sulfates (SO42-) are soluble except BaSO4, PbSO4, Hg2SO4, CaSO4, SrSO4, and Ag2SO4
2. All sulfide (S2-) are insoluble except Group 1 and Group 2 and ammonia (NH41+).
3. All chromate (CrO42-) are insoluble except those of Group 1 and ammonia (NH41+), CaCrO4, and SrCrO4.
4. All hydroxides are insoluble except those of Group 1, ammonia (NH41+), Ba(OH)2, Sr(OH)2 and Ca(OH)2.