Question

(aq) (1) Mg(OH)2 is partially dissolved in water: Mg(OH), (s) = Mg2+ (aq) + 2OH Write the Kop expression for Mg(OH)2 : Kp = (2) Solid AgCl is partially dissolved in water: AgCl 2 Ag+ + CI''. If the molar solubility is known as [Ag +) = [CI''] = 1.3x 10 M, AgCl Kip =- (a) 1.3 x 10 (b) 1.69 x 10-10 (c) 2.6 x 10 (d) none of these (3) At 25 °C, the solubility of solid AgCl in a solution containing Agt should be its solubility in pure water. (a) greater than (b) less than (c) the same as (4) CaF, solid has Kp = 3.9 x 10", PbCl2 solid has Kp = 1.7 x 109. which one has larger solubility in water? (a) CaF2 (b) PbCl2 (c) Both are the same (5) Solid MgCO3 is slightly dissolved in water : MgCO3 (8) = Mg 2+ (aq) + CO2 (aq). The solubility product of MgCO, is: Ksp = 3.5 x 10%, the molar solubility of MgCO3 i.e. (Mg2+ ) or (COP) is (a) 3.5 x 10M (b) 1.75 x 108 M (c) 10 M (d) 1.87 x 10-M (6) ZnS solid has Ksp = 2x 10-25, CuS solid has Ksp = 6x 10", when very slowly adding HS gas to 0.1 M (Zn) and 0.1 M (Cu) solution, which solid will precipitates first? (a) ZnS (b) Cus (c) at the same time (7) When a liquid freezes to become solid, the entropy change of the system (a) AS sys > 0 (b) AS sys < 0 (c) AS sys = 0 (d) AS sys = AG (8) When liquid is vaporized to become gas, the entropy change of the system (a) AS > 0 (b) AS <0 (c) AS = 0 (d) AS = AG

Answer 1

Mg(ou S Mgth 4 201 S 25 Kop - [Mg +2] [ou]² = S(25) - 453 ② Agce - Agt +cê kop: [Ag] [ca] - (1.3x185) 2 - 1.6981510 An: Solubility of solid Agce in solution contains Agt should be less than its solubility. in pure mater. Am Pearon. Common in effect. (3 CaF2 pbcl kop= 3.9610 Kop= 1.7810 Ksp pouy kop cafe 1 PbCl2 is more soluble in 420 When liquid freezes to solid, bA Ssys To when liquid is vaporised at AS systo I 6

s, M, соз - S S s Kepa Sh 3.5x108 - se S: $* 1.87 X10 M -4 . [Mg + 2] = [102] = 1.87X10 AM An: @ 67 zus Ksp = 2x 102 Cus kop = 6x 1037 Ksp ans) Ksp cus by Cus will ppt out first A