Some Solubility Rules for Common Salts and Bases Soluble salts and bases Symbols Names Exceptions - NO 3 Nitrates None - C2H3O2 Acetates Silver acetate (AgCH 3COO) is only moderately soluble. - (CH 3COO ) Cl -, Chlorides, Silver halides (Ag X), - - X X Br , and I bromides, and mercury(I) halides (Hg 2 2), *lead(II) halides (Pb 2), and mercury(II) iodide (HgI 2), iodides. *Note: PbCl 2 is slightly soluble in cold water and moderately soluble in hot water. 2- SO 4 Sulfates Barium sulfate (BaSO 4), and lead(II) sulfate (PbSO 4). Calcium sulfate (CaSO 4), Mercury(I) sulfate (Hg 2SO 4), and silver sulfate (Ag 2SO 4) are slightly soluble. - The corresponding bisulfates are more soluble. They are: (HSO 4 ) (Bisulfates) calcium bisulfate [Ca(HSO 4)2], mercury(I) bisulfate [Hg 2(HSO 4)2], and silver bisulfate [Ag (HSO 4)2] Na +, Cations of Some uncommon ones*. + K , + sodium, NH 4 potassium, and *Insoluble: Na 4Sb 2O7 , K 2NaCo(NO 2)6 , (NH 4)2NaCo(NO 2)6 , K 2PtCl 6 , and (NH 4)2 ammonium PtCl 6 . Insoluble salts and bases Symbols Names Exceptions 2- 3- 2- CO 3 , PO 4 , SO 3 , and Carbonates, Carbonates, phosphates, sulfites, and silicates of alkali metals 2- + + SiO 4 . such as sodium (Na ) and potassium (K ), and of ammonium phosphates, + (NH 4 ). sulfites, and silicates. Many acid phosphates, such as Mg(H 2PO 4)2 and Ca(H 2PO 4)2. 2- CrO 4 Chromates Na 2CrO 4, K 2CrO 4, (NH 4)2CrO 4, MgCrO 4, CaCrO 4, Al 2(CrO 4)3, NiCrO 4. 2- - O , & OH Oxides and NaOH, KOH, and Ba(OH) 2. Ca(OH) 2 is slightly soluble. hydroxides 2- S Sulfides Na 2S, K 2S, (NH 4)2S; and those combined with alkaline earth metals such as MgS, CaS, SrS, and BaS. Note: Sulfides of aluminum (Al 2S3) and chromium(III) (Cr 2S3) hydrolyze to form hydroxides which are insoluble. This means a double displacement reaction occurs with water where aluminum or chromium combine with the hydroxide ion (OH -) to form in insoluble precipitate: Aluminum: Al 2S3(aq) + 6H 2O(l) → 2Al(OH) 3(s) + 3H 2S(aq) Chromium: Cr 2S3(aq) + 6H 2O(l) → 2Crl(OH) 3(s) + 3H 2S(aq) + Ag The cation of Silver nitrate (AgNO 3) and silver silver chlorate (AgClO 4). Silver acetate (AgCH 3COO) and silver sulfate (Ag 2SO 4) are only moderately soluble. .