Question

22%D 22:27 513 395 5 - Question 3 (13 marks) TODO of ☺ ☺ + B Uzxy , s xx = -snapped = non-lin 7 i 363)-6=3" The solubility product constant of Mg(OH)2, Ksp, is given as 7.1 x 10-12. (a) If a solution is 0.0303 M with respect to Mg2+ ion, what is the molar concentration of OH required to start the precipitation of Mg(OH)2? (2 marks) (b) Calculate the pH of the solution that results when 0.081 g of Mg(OH)2 is mixed with 75.0 ml of 0.04 M HCl. (5 marks) (c) Calculate the pH of the solution that results when 0.077 g of Mg(OH)2 is mixed with 15.0 ml of 0.04 M HCl. (6 marks) Page 2 of 7 Question 4 (11 marks) (a) A sample mixture containing compounds D and E was separated by normal-phase high- performance liquid chromatography. The chromatogram obtained is shown below. Detector Signal

Answer 1

0.0013 mol Moles of Mg 104 . 0.0779 58:32 gimoi Moles of Hill = 0.04 MX 15.0 pat looo mtL = 0.000 60 mol I mol of Mg(OH) - 2 mol of the 0.0013 mol of Mg(OH) = 280.0013 mol = 0.0026 mol tie is limiting in this case. so unreacte Atgtong 0013-corole 2 mol the I o.voodo mol te = = Imol of Mg(OH)2 1 x 0.00060 = 0.00030 mol of Мяси),