Question

7) At 50°C the value of Kw is 5.5 x 10-14. At what pH is waster neutral at 50°C. A) 6.63. B) 5.50. C) 7.00 D) 7.37. 8) A solution with a hydroxide ion concentration of 4.15 x 10-4 M is and has a hydrogen ion concentration of A) basic, 2.41 x 10-10 M B) acidic, 2.41 * 10-10 M C) basic, 2.41 x 10-11 M D) acidic, 2.41 x 10-11 M 9) Which one of the following salts, when dissolved in water, produces the solution with the lowest PH? A) NaCl B) AlCl3 C) NH4C D ) MgCl2 10) Calculate the pH for an aqueous solution of pyridine that contains 3.15 x 10-4 M hydroxide ion. A) 10.50 B) 3.15 x 10-4 C) 3.17 x 10-11 D) 3.50 11) What is the hydroxide ion concentration of a lye solution that has a pH of 12.20? A) 1.58 x 10-2 M B) 6.31 x 10-13 M. C) 12.20 M D) 1.80 M 1 12) What is the pH of a solution prepared by mixing 100.00 mL of 0.20 M HCl with 50.00 mL of 0.10 M HCI? Assume that the volumes are additive. A) 0.52 B) 1.70 C) 0.15 D) 0.78

Answer 1

Kw = CH +3 [ot] = 5.5 4.1014 but for water, [H+] = [ot] (neutral) - 7 [H+] = √5.5x1014 = 2.345 x 10 m pH = -log (H+] = 6.63 Answer: A) 6.63 8) [OH-] = 4.15 x 104m hydroxide ion solution is bassic in nature pOH = -log [OH-] = 3.382 pH + pH = 14 pH = 14-3-382. = 10.618 pH = -log (14+] = 10.618 [14+] = 10 10.018 = 2.41x10 m - c) basic, 2.41x10 m. Answer:

9 c) whil - gives a weak base in aqueous solution, whose pott is high pH is low.

10) POH - -log(3:15 x 104) = 3.5 pH = 14-3.5= 10.5 A) 10.50 ). 94 =14-pH = 14 - 12.20 = 1.50 - log [OH-] = 1.80 [OH-] = 101.80 = 0.01585.m. Answer: A) 1.58x10 m. - 2

12) total number of molis of H+ = (O.1 LX 0.20m) + (0.05 LX0.10m) = 0.025 moles 14+2 = 0.025 mol = 0.167 m. 0. ISOL pH = -log (0-167) = 0.78 Answer: 0) 0.78