solubility equilibria lead (ii) iodide precipitates when potassium iodide is mixed with lead (ii)...

of 13 /13
Solubili ty Equilibr ia Lead (II) iodide precipitates when potassium iodide is mixed with lead (II) nitrate. Graphic: Wikimedia Commons user PRHaney

Author: brianna-bludworth

Post on 31-Mar-2015

214 views

Category:

Documents


1 download

Embed Size (px)

TRANSCRIPT

  • Slide 1

Slide 2 Solubility Equilibria Lead (II) iodide precipitates when potassium iodide is mixed with lead (II) nitrate. Graphic: Wikimedia Commons user PRHaney Slide 3 K sp Values for Some Salts at 25 C Slide 4 Solving Solubility Problems For the salt AgI at 25 C, K sp = 1.5 x 10 -16 AgI(s) Ag + (aq) + I - (aq) I C E O O +x x x 1.5 x 10 -16 = x 2 x = solubility of AgI in mol/L = 1.2 x 10 -8 M Slide 5 Solving Solubility Problems For the salt PbCl 2 at 25 C, K sp = 1.6 x 10 -5 PbCl 2 (s) Pb 2+ (aq) + 2Cl - (aq) I C E O O +x +2x x 2x 1.6 x 10 -5 = (x)(2x) 2 = 4x 3 x = solubility of PbCl 2 in mol/L = 1.6 x 10 -2 M Slide 6 Solving Solubility Problems For the salt AgI at 25 C, K sp = 1.5 x 10 -16 AgI(s) Ag + (aq) + I - (aq) I C E O O +x x x 1.5 x 10 -16 = x 2 x = solubility of AgI in mol/L = 1.2 x 10 -8 M Slide 7 Predicting Precipitate Formation Use the initial concentrations of ions in solution in the solubility product constant expression to calculate Q sp. If Q sp < K sp the solution is unsaturated and no precipitate will form. If Q sp = K sp the solution is saturated and no change will occur. Slide 8 Predicting Precipitate Formation, continued If Q sp > K sp a precipitate will form, reducing the concentrations of the ions in the solution until the product of their concentrations in the K sp expression equals the numerical value of K sp. Slide 9 Predicting Precipitate Formation, continued Do practice problems on pg. 619 Slide 10 Predicting Precipitate Formation, continued Answers: 25. a. Qsp > Ksp so a precipitate of PbF2 will form. b. Qsp < Ksp so no precipitate will form 26. A precipitate will form. Slide 11 The Common Ion Effect Why is PbCrO 4 less soluble in aqueous solution of K 2 CrO 4 than in pure water? The K 2 CrO 4 solution contains CrO 4 2 ions before any PbCrO 4 dissolves. Slide 12 The Common Ion Effect (cont.) A common ion is an ion that is common to two or more ionic compounds.common ion The lowering of the solubility of a substance because of the presence of a common ion is called the common ion effect.common ion effect Slide 13 Solving Solubility with a Common Ion For the salt AgI at 25 C, K sp = 1.5 x 10 -16 What is its solubility in 0.05 M NaI? AgI(s) Ag + (aq) + I - (aq) I C E 0.05 O +x 0.05+x x 1.5 x 10 -16 = (x)(0.05+x) (x)(0.05) x = solubility of AgI in mol/L = 3.0 x 10 -15 M Slide 14 Precipitation and Qualitative Analysis