Question

3. Barium hydroxide Ba(OH)2 was dissolved in pure water at 5 Cuntil a saturated solution was obtained. The pH of this solution was found to be 12.25. a) (2 marks) What is the molar solubility of Ba(OH), in pure water at this temperature? Express your answer in mol/L. Show your work. b) (1 mark) What is the Kp of Ba(OH)2 at this temperature? Show your work. c) (0.5 marks) If Ba(OH)2 was added to a solution already containing 0.100 M NaOH, would its molar solubility increase, decrease, or stay the same relative to that in pure water? INCREASE DECREASE STAY THE SAME d) (0.5 marks) If Ba(OH), was added to a solution already containing 0.100 M HNO, would its molar solubility increase, decrease, or stay the same relative to that in pure water? INCREASE DECREASE STAY THE SAME Page 4 of 9

Answer 1

-1.75 1.78X10 10 3. Given, pH, 12:25 FOR SATURATED Ba(OH), Sowrow pH + polt - 14.00 5 POH . 14.00 - 12.25 = 1.75 [ot] = 101.45 - 1.78 x 10²m a) Ba(OH), = Ba²+ + 2045 1 mole Ba(OH), PRODUCTS 2 moli ot [ow] : 1.78 x162 m - MOLAR solubility of Ba (OH) = 1048x10²m = 18.90x10 ml lon 3 1 0 Ksp = [Ba2+) (04-)" [Ba²+] = 8.80x10² M (OH) = 1.78 x10 m. i ksp = (8.80 x103) (1.78 x102)2 = (do 82 xjós 2 2 - 1.78x10 M.

woulo DECEASE c) IN 0.100m NaOH, solubility of Da (OH)2 QUE TO common Ion (OH HERE) Effect- Ba(OH)₂ → Be 24 a 2015 PRESENCE of OH (From Naoh) PUSHES EQUILIBRIUM TOWARS Ba(OH)₂ ottus DECREASING ITS solubiery. d) In 0.100 19 HNO3, molara sole Bisery INCREASE H from Halog REAG WITH OH, so EQUILIBRIUM is pushED TOWARDS RIGHT , thus molara soluBidery increases. HD FAIT