Ag+]2[CrO42-] = (2s)2(s)Р1-1型: ? AgCl (s) = Ag+ (aq) + Cl- (aq) ? S S ? Ksp = [Ag+] [Cl-] = S2Р溶度积与溶解度Р例. 查表知PbI2的Ksp为 1.4 × 10-8, 估计其溶解度 s 。?解: ? PbI2 (s) = Pb2+ (aq) + 2 I- (aq) Ksp = [Pb2+ ][I-]2? [Pb2+] = s? [I-] = 2s ? Ksp = [Pb2+ ][I-]2 = (s)(2s)2 = 4s3? s = (Ksp/4)1/3 = (1/4 × 1.4 × 10-8)1/3 = 1.5 ×10-3 (mol/L)Р溶度积与溶解度Р要注意: ? 对于同种类型化合物而言, Ksp , S 。? 但对于不同种类型化合物之间,不能根据Ksp来比较S的大小。Р例已知Ksp,AgCl= 1.8 10-10,Ksp,Ag2CrO4=1.1 10-10,试求AgCl和Ag2CrO4的溶解度Р解:(1)设AgCl的溶解度为S1? AgCl(s) Ag+(aq) + Cl-(aq)?平衡时: S1 S1? S1 = 1.33 10-5 (mol/L)?(2)设Ag2CrO4的溶解度为S2? Ag2CrO4(s) 2Ag+(aq) + CrO42-(aq)?平衡时: 2S2 S2? S2 = 3.02 10-4 (mol/L)Р二、沉淀的生成(Precipitation)РBaSO4 (s) = Ba2+(aq) + SO42-(aq) ? Ksp= [Ba2+ ][SO42–]? 离子积 Q=C Ba2+ C SO42–? Q 与 Ksp 的关系: ? 溶度积原理? 1 Q = Ksp,平衡状态? 2 Q > Ksp,析出沉淀? 3 Q < Ksp,沉淀溶解