Chem 215, Fall 2007 Problem Set 6Due Friday, Oct. 12, 2:00 PM ed Ch 8: 71, 81, 83, 93 Name: ___________________________ Ch 10:13, 19, 25, 31, 41, 51 Undergrad TA Name: _________________________ Lab Day: ________________________ 1.The Kspfor Cu(OH)2is 1.6 x 10-19. The complex Cu(NH3)42+is produced by mixing Cu2+with ammonia: Cu2+ (aq) + 4NH3(aq) ⇔Cu(NH3)42+(aq) K = 1.0 x 1013a)Calculate the equilibrium constant for the following reaction: Cu(OH)2 (s) + 4NH3(aq) ⇔Cu(NH3)42+(aq)+ 2OH- (aq) b) Calculate the solubility (in mol/L) of Cu(OH)2in 3.0 M NH3(aq).
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Chem 215, Fall 2007 Problem Set 6Due Friday, Oct. 12, 2:00 PM 2.Sand is primarily silica, SiO2. It can react with water to form silicic acid: SiO2(s) + 2H2O(l) ⇔H4SiO4(aq) K = 2 x 10-3Silicic acid is a weak acid: H4SiO4(aq) + H2O ⇔H3SiO4-(aq) + H3O+(aq) pKa= 9.46 a)Will silica be more soluble in an acidic or basic solution? Why? b)Calculate the molar solubility (in mol/L) of silica at a pH of 7.0 and a pH of 10.0.