Exercise 1 (4 marks): “The pH Scale” Milk of Magnesia has a pH of 10. 1.1) What is the hydronium ion concentration [H3O+]? ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... 1.2) What is the pOH? ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... 1.3) What is the hydroxide ion concentration [OH-]? ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... 1.4) Is this commercial product neutral, basic, or acidic? Why? ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... Page 1 of 3 Exercise 2 (3 marks): “Reduction-Oxidation” 2.1) Find the normality (N) of a solution containing 6.6 g of ascorbic acid (Mwt = 127.12 g/mol) in 250 mL if the relevant half-reaction is: H2O + ⇋ Ascorbic acid + 2H+ + 2eDehydroascorbic acid ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... Exercise 3 (3 marks): “Weak Base” 4.1) Find the pH of 0.1 M ammonia (NH3). Kb for ammonia is 1.75 x 10-5 ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... Page 2 of 3 Exercise 4 (5 marks): “Buffer Solution” 4.1) A buffer was prepared by adding 0.5 L of 0.1 M weak acid (HA; Ka = 10-5) to 0.5 L of 0.05 M its conjugate base. Find the pH. ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... ..................................................................................................................................................................................... Good luck ! Page 3 of 3
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