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EX 1 KEY - CHM 2046 EXAM 1 February 9 2012 Please Bubble in...

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Unformatted text preview: CHM 2046 EXAM 1 February 9, 2012 Please Bubble in A as the Test Form Code at the Top Right of Your Answer Sheet. 1. The “conjugate acid” in the reaction of H2SO4 with excess NaOH i ' , p (a) H2SO4 (b) HSO4' (c) S04"2 .120 (e) H30+ 2. In which of the following are the species listed in order of increasing pH? (a) KCl, NH4Cl, HNO3, KOH, N aC2H302 (b) HNO3, KCl, NH4Cl, KOH, NaC2H302 c NH4Cl, HNO3, KCl, KOH, NaC2H302 8HNO3, NH4Cl, KC], NaC2H302, KOH (e) none of these 3. The conjugate acid and conjugate base of bicarbonate ion, HCO3‘, are, respe ively: (a) H30+ and OH‘ (b) H30+ and C032— (c) H2CO3 and OH‘ ‘H2C03 and C032— (e) C03? and 0H— 4. As water is heated, its pH decreases. This means that: (a) the water is no longer neutral (b) [H+] > [OH‘] (c) [OH‘] > [H+] .Kw changes its value (e) None of these is correct 5. Calculate the pH of a 1.9 M solution of H 03. (a) 0.28 (b) —0.64 0.28 (d) 14.28 (c) 13.72 6. In a solution prepared by dissolving 0.100 mol of propionic acid in enough water to make 1.00 L of solution, the pH is observed to be 1.35. Which is the closest to the value of Ka for propionic acid (HC3H502)? (a) 2.0x 10'2 .3.6x 10‘2 (c) 4.5x 10—2 (d) 5.0x 10‘12 (e) none ofthese 7. Calculate the p_H of a 0.10 M solution of Ba(OH)2. .1330 (b) 0.70 (c) 1.00 (d) 13.00 (e) none ofthese 8. Which aqueous solution (all 0.1 M) will have the highest (most basic) p_H? (a) NH4N03 (b) NaHSO4 (c) NaHCO3 .Na2C03 (e) KNO3 9. Which aqueous sol . ' (all 0.1 M) will have the lowest (most acidic) p_H? (a) NH4NO3 WaHSO4 (c) NaHCO3 (d) Na2C03 (e) KNO3 10. What will be the overall effect on the concentrations and n values when volume is increased? N204 (g) H 2 N02 (g) A. [N204] decreases B. [N204] increases C. nNQ2 increases D. nN204 increases (a)b&d (b)a&d (c)a,c&d .a&c (e)b&c 11. Using data from the acid-base table, find the value of K for this equation. H3PO4 + 2NH3 H HPO42'+ 2NH4+ K: .15 x 109 (b) 2.2 x 1016 (c) 1.3 x 107 (d) 1.6 x 1011 (e) 2.3 x 10'12 12. Gaseous ammonia was introduced into a sealed container a At equilibrium, [NH3]=0.0225 M, [N2]=0.114 M, and [H2]—0 342 M. 2331302;) H N2(g)+3H2(g) Calculate the value of Kc. 9.01 (b) 10.1 (c) 9.007 (d) 10.5 (e) 1.73 13. If H803" reacts as an acid, with HPO4'2 acting as a base, the products will be which of these? (a) 803'2 + PO4'3 (b) H2803 + PO4‘3 (c) H2803 + H2P04'2 803'2 + H2PO4' (e) (5093(1) O4)2 14. For which solution would it be valid to calculate the pH using [H3O+] = (Ka - C0)“2 ? 0.010 Mst (b) 0.010 MNaHSO4 (c) 0.010 Msto3 (d) 0.010 MNaOH (e) 0.010 Msto4 15. If water is added to a NH3 solution which of these will increase? NHs (361) + H20 (t) H NH4+ (aq) + OH' (361) (A) nOH- (B) pH (C) a(degree of ionization) (a) a only (b) b only (c) c only (d)a,b&c ®&c \ The next 2 items refer to a 0.015 M (as prepared) solution of weak acid HX. The observed pH is 2.40. It is suggested you first calculate [H3O+], [HX] and [X'] at equilibrium. 16. What is the degree of ionization (a) of HX for this solution? (a) 3.8% ’7% (c) 36% (d) 44% (e) 73% 17. Which is the closest to the value of K3 for HX? (a) 1.6 x 10'5 (b) 1.1 x 10'3 @15 x 10'3 (d) 4.0 x 10'3 (e) 0.027 \ 18. For the equilibrium N204(g) <—> 2 N02(g), AH = 57.1 kJ/mol. For this reaction, Kp = 1.4 at 250 C. What is K2 at 373 K? (a) 1.0 x 102 .14 x 102 (c) 3.7 x 104 (d) 9.3 x 104 (e) 5.0 19. A carefully calibrated pH meter reads 4.321. Which best represents |H§O+|? (a) 5 x 10'5M (b) 4.8 x 10'5 M @4.78 x 10'5M (d) 4.775 x 10'5 M (e) 9.679 M 20. What is the net ionic equation for the reacti the bottom margin of your answer sheet. 16370.. + 2M6?) (Ea H?O,1‘+ 20%;— , on of H3PO4 with excess NH3 (aq)? Write your answer in ...
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