The common ion effect, predicting precipitation:Read pg. 580 – 582 (common ion effect section only). Do PE 20 - 21PbI2(s)Pb2+(aq)I –(aq)1200.10x2x0.10 + 2xxRICEKsp = [x] [0.10 + 2x]2= 7.9 x 10–9Ksp = [Pb2+(aq)] [I–(aq)]2Example 14.17 (pg. 581)Molar solubility of PbI2? Ksp = 7.9 x 10–9Concentration of NaI is 0.10, thus [I–] = 0.10NaI(s) ↔Na+(aq) + I–(aq)x is small, thus we can ignore 2x in 0.10 + 2xKsp = [x] [0.10]2= 7.9 x 10–9, x = 7.9 x 10–7MPredicting when precipitation occursRead pg. 582. Do PE 22, 23Similar to Kc vs. mass action expression to predict if equilibrium exists (and which way it will shift)E.g. in example 14.18PbCl2(s) ↔Pb2+(aq) + 2Cl–(aq)(NaCl and Pb(NO3) are soluble according to the solubility rules; they will not precipitate)Ksp = 1.7 x 10-5, [Pb2+][Cl–]2= 3.4 x 10–5Ion product is large … to reduce, equilibrium must shift left … precipitate formsPredicting when precipitation occurs
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This note was uploaded on 04/12/2011 for the course CHEM 1010 taught by Professor Marshall during the Spring '11 term at North Texas.