Sample Questions - Chapter 18

Aqueous Equilibrium - Acids/Bases/Salts

Examples of
Multiple Choice Questions

1.: Which one of the following is a weak acid?; (a) HNO₃; (b) HI; (c) HBr; (d) HF; (e) HClO₃
2.: Which salt is not derived from a strong acid and a strong soluble base?; (a) MgCl₂; (b) Ba(NO₃)₂; (c) LiClO₄; (d) CsBr; (e) NaI
3.: Which one of the following is a strong electrolyte?; (a) H₂O; (b) KF; (c) HF; (d) HNO₂; (e) (CH₃)₃N
4.: In a sample of pure water, only one of the following statements is always true at all conditions of temperature and pressure. Which one is always true?; (a) [H₃O⁺] = 1.0 x 10^-7 M; (b) [OH^-] = 1.0 x 10^-7 M; (c) pH = 7.0; (d) pOH = 7.0; (e) [H₃O⁺] = [OH^-]
5.: If K_w is 2.9 x 10^-15 at 10^oC, what is the pH of pure water at 10^oC?; (a) 6.72; (b) 7.00; (c) 7.27; (d) 7.53; (e) none of these
6.: The pOH of a solution of NaOH is 11.30. What is the [H⁺] for this solution?; (a) 2.0 x 10^-3; (b) 2.5 x 10^-3; (c) 5.0 x 10^-12; (d) 4.0 x 10^-12; (e) 6.2 x 10^-8
7.: The [H₃O⁺] in a 0.050 M solution of Ba(OH)₂ is:; (a) 1.0 x 10^-5 M; (b) 5.0 x 10^-2 M; (c) 1.0 x 10^-13 M; (d) 5.0 x 10^-10 M; (e) 2.0 x 10^-5 M
8.: What is the approximate pH of a solution labeled 6 x 10^-5 M HBr?; (a) 4.2; (b) 4.5; (c) 5.8; (d) 9.8; (e) 8.2
9.: What is the pH of 500 mL of solution containing 0.0124 grams of Ca(OH)₂?; (a) 11.04; (b) 9.68; (c) 2.96; (d) 3.17; (e) 10.83
10.: The pH of a solution is 4.80. What is the concentration of hydroxide ions in this solution?; (a) 4.2 x 10^-9 M; (b) 1.6 x 10^-5 M; (c) 3.6 x 10^-12 M; (d) 6.3 x 10^-10 M; (e) 2.0 x 10^-8 M
11.: A solution in which [H⁺] = 10^-8 M has a pH of ___ and is ___.; (a) 8, acidic; (b) 6, basic; (c) -6, basic; (d) -8, neutral; (e) 8, basic
12.: The pH of a 0.02 M solution of an unknown weak acid is 3.7. what is the pK_a of this acid?; (a) 5.7; (b) 4.9; (c) 3.2; (d) 2.8; (e) 3.7
13.: What is the approximate pH of a solution labeled 0.050 M HClO?; (a) 5.1; (b) 3.9; (c) 4.4; (d) 2.1; (e) 7.6
14.: What is the pH of a solution labeled 0.30 M (CH₃)₃N?; (a) 9.5; (b) 10.8; (c) 9.2; (d) 11.7; (e) 12.2
15.: Which of the following solutions has the lowest pH at 25^oC? (No calculations required.); (a) 0.2 M sodium hydroxide; (b) 0.2 M hypochlorous acid; (c) 0.2 M ammonia; (d) 0.2 M benzoic acid; (e) pure water
16.: A 0.10 M solution of a weak acid, HX, is 0.059% ionized. Evaluate K_a for the acid.; (a) 3.8 x 10^-9; (b) 6.5 x 10^-7; (c) 7.0 x 10^-6; (d) 4.2 x 10^-6; (e) 3.5 x 10^-8
17.: What is the percent ionization of an 1.2 M HF solution?; (a) 2.4 %; (b) 4.2 %; (c) 0.84 %; (d) 0.082 %; (e) 0.22 %
18.: Which of the following weak acids ionizes to give the strongest conjugate base?; (a) HClO; (b) CH₃COOH; (c) HF; (d) HNO₂; (e) HCN
19.: Which of the following is true about a 0.10 M solution of a weak acid, HX?; (a) [X^-] = 0.10 M; (b) pH = 1; (c) [HX] > [H⁺]; (d) [H⁺] = 0.10 M; (e) both b and d
20.: Calculate the hydrolysis constant for the cyanide ion, CN^-.; (a) 2.5 x 10^-5; (b) 1.0 x 10^-7; (c) 4.0 x 10^-10; (d) 5.6 x 10^-10; (e) none of these
21.: Calculate the pH of a 0.50 M solution of NaNO₂.; (a) 12.18; (b) 5.48; (c) 1.82; (d) 8.52; (e) 7.00
22.: What is the concentration of a sodium acetate solution if the pH of the solution is 9.19?; (a) 0.30 M; (b) 0.43 M; (c) 2.1 M; (d) 0.068 M; (e) 0.59 M
23.: What is the pH of 0.060 M NH₄Cl?; (a) 5.06; (b) 5.12; (c) 5.18; (d) 5.24; (e) 5.35
24.: What is the concentration of ammonium chloride in a solution if its pH is 4.80?; (a) 0.25 M; (b) 0.30 M; (c) 0.45 M; (d) 0.60 M; (e) 0.15 M
25.: The pH of 0.15 M trimethylammonium chloride, (CH₃)₃NHCl, a salt, is 5.34. What is the percent hydrolysis?; (a) 0.0031 %; (b) 0.0068 %; (c) 0.0094 %; (d) 0.011 %; (e) 0.022 %

Answers:

1. (d) 2. (a) 3. (b) 4. (e) 5. (c) 6. (a) 7. (c) 8. (a) 9. (e) 10. (d) 11. (e) 12. (a) 13. (c) 14. (d) 15. (d) 16. (e) 17. (a) 18. (e) 19. (c) 20. (a) 21. (d) 22. (b) 23. (d) 24. (c) 25. (a)

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