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G_190323_2009-05-28 - 2 6 “ PAGE 1 CHE 1113 TEST III DR...

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Unformatted text preview: 2. 6. “ PAGE 1 CHE 1113 TEST III DR. POWELL JULY 23, 2008 Please print your name on both the test paper and the Scan Tron form. SECTION1. MULTIPLE CHOICE (4 points each). What is the conjugate base of OH' a) H20 b) H3O+ c) 0‘ d) Ho+ 0 Three weak acids and their Ka values are: Acetic acid, Ka = 1.8 x 10‘5; Hypochlorous acid, Ka = 1.1 x 10'8; Hypobromous acid, Ka = 2.1 x 10'9 Which of the following is the strongest base? a) CH3000’ .OBr' c) OCI' d) HOBr e) HOCI What is the pH of 1.50 M HCI? aY/0000 )9/0150 c) 14.2 /d’)’1.50 @0176 Which of the following buffer solutions should have the lowest pH? a) 0.025 M KNOZI 0.050 M HNo2 o 5 b) 0.050 M KNOZI 0.050 M HNo2 l c) 0.040 M KN02/ 0.025 M HNo2 l 0 @ 0.050 M KN02/ 0.025 M HNo2 .1 e) 0.025 M KN02/ 0.040 M HNo2 1927 Which of the following 0.100 M solutions has the highest pH? a) HA, K;,.=2x10'3 b) HA, Ka = 8.0 x 106 c) HCI d HA, Ka = 3.2 x 10*1 NH3, Kb =1.8 x 10'5 SECTION 2. PROBLEMS (6 points each). A 100. -mL saturated solution of magnesium oxalate, MgCZO4, contains 0.104 g of M90204. PAGE 2 7. Calculate the pH of 0.0584 M solution of KOH. a) 1.23 b) 8.54 c) 9.77 d) 12.77 6) 4.23 A 0.100 M solution of bromoacetic acid is,11.20% ionized. What is the K3 for this acid ? 91.41x10'3 al Is ; .oIlQa Rf 1.74x10-4 , 0,, 0) 0.0112 ' . ”f. .- 1052855 d) 2.01 x10-3 ‘ .Oll2 e) 1.25x10'3 9° 9. A 0.0350 M solution of ephedrine has a pH of 11.33. Calculate the Kb for ephedrine. a) 6.25x1022 (Ll - (1,53 — )0 “’7 00.21 b) 4.68x1012 lg - c) 2.14x103 155—" 00350 d) 4.57x106 1.39x10“1 10. How many grams of sodium lactate should be added to 1 .—00 L of 0.120 M lactic acid(HCsH503) to form a buffer solution with pH 4. 00? 56 5‘ (/7 .7 (Ka for Lactic acid— - 1.40 x 10-4) 7? (200,94 .I20 05 2%: Q a) 9.55 g . I 4 & MM 5) 7 b) 10.8 g , 3.35 g .. , ‘10 . 07% $54 /0 @ 19.0 g ’ 3 IS. /5 )' 13.5 g ANSWER THE FOLLOWING QUESTIONS ON THE TEST PAPER YOU MUST SHOW ALL OF YOUR WORK IF YOU WISH TO RECEIVE ANY CREDIT!! 1. Consider a 0.375 M aqueous solution of NaF : a) Write the appropriate chemical equation for this species reaction with water. (4 POINTS) MOKF 4’ H990 7% H30 1. Lil—0K b) Given that Ka for HF = 7.20 x 104 , calculate the pH of this solution. (8 POINTS) Wfll ’ WM? fig Mm ~ 5 ftlrllfizéh slog (W55 PAGE 3 Calculate the solubility, in g/100mL, of La(103)3 in a 0.010 M K103 solution. {5% 903 ‘3 Ksp for La(103)3 = 8.10 x 10‘14 (10 POINTS) ' What is the pH of a 1.0-L solution w IC is 0.145 M propionic acid (CH3CH2COOH) . nd 0.130 M sodium propionate after the addition of 0.0430 mol HBR? Assume no volume change. (Ka for propionic acid = 1.30 x 10—5) (10 POINTS) / 0? ’2 a .130 5.0430 @ f5! {9173) 0'00? Vb: u,gq+r.aafi 17! GIHfi‘) 4 What is the pH 0f 0.284 M HIO? Ka for HIO = 2.30 x 10'11 (5 POINTS) —4 l.0xl0' , -4/ 9L /»~—/<j" ”35XD y 230W I @5934 The solubility of mercury(l|)hydroxide is 1.84 x 10'9 M in pure water. What is the Ksp? (5 POINTS) ...
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