7.13 Practice Problems

Attempt these problems as if they were real exam questions in an exam environment.

Only look up information if you get severely stuck. Never look at the solution until you have exhausted all efforts to solve the problem.


  1. What is the Ka for a 0.05 M monoprotic weak acid solution that has a pH of 3.85 (at 25 °C)?

    1. 4.0 × 10–7
    2. 1.4 × 10–4
    3. 2.3 × 10–6
    4. 3.5 × 102
    5. 3.85

    Solution


  2. What is the pH of water at 60 °C? Kw = 9.311 × 10–14

    1. 6.5
    2. 6.9
    3. 7.0
    4. 7.4
    5. 8.2

    Solution


  3. What is the pOH of an aqueous solution containing 0.40 M HI (at 25 °C)?

    1. 1.40
    2. 3.24
    3. 7.68
    4. 8.43
    5. 13.6

    Solution


  4. Identify the Brønsted-Lowry acid in the following reaction.

    \[\mathrm{NO_3}^-(aq) + \mathrm{H_3O^+}(aq) \rightleftharpoons \mathrm{H_2O}(l) + \mathrm{HNO_3}(aq)\]

    1. H2O
    2. HNO3
    3. H3O+
    4. NO3
    5. none of these

    Solution


  5. A substance is found to be an electron-pair donor. What acid/base definition best describes this substance?

    1. Arrhenius base
    2. Lewis base
    3. Brønsted-Lowry acid
    4. Lewis acid

    Solution


  6. 0.25 mol of a strong, monoprotic acid is dissolved in water resulting in a 500 mL aqueous solution. What is the pH (at 25 °C)?

    1. 0.3
    2. 0.6
    3. 1.2
    4. 2.4
    5. 3.3

    Solution


  7. The Ka for hydrofluoric acid is 7.2 × 10–4 at 25 °C. What is the corresponding Kb for its conjugate base?

    1. 7.4 × 10–18
    2. 6.7 × 10–14
    3. 1.4 × 10–11
    4. 7.2 × 10–10
    5. 7.0

    Solution


  8. Which acid is the strongest? Values are given at 25 °C.

    1. HNO2, pKa = 3.39
    2. HF, pKa = 3.14
    3. HCN, pKa = 9.21
    4. CH3COOH, Ka = 1.8 × 10–5
    5. H2CO3, Ka = 4.3 × 10–7

    Solution


  9. What is [H3O+] (in M) for a sample of pure water at 45 °C? Kw = 3.94 × 10–14

    1. 3.41 × 10–8
    2. 8.33 × 10–4
    3. 4.21 × 106
    4. 6.70
    5. 1.98 × 10–7

    Solution


  10. The pOH of an aqueous solution is 6.22 (at 25 °C). What is the pH of the solution?

    1. 6.44
    2. 6.84
    3. 7.00
    4. 7.78
    5. 8.02

    Solution


  11. A 0.15 M monoprotic acid is dissolved in pure water and the pH of solution is 2.43. What is the percent ionization of the acid?

    1. 0.11%
    2. 2.48%
    3. 6.31%
    4. 8.44%
    5. 12.86%

    Solution


  12. Which of the following conjugates will react with water to affect the pH of solution?

    1. CO32–
    2. Cl
    3. NO3
    4. K+
    5. Br

    Solution


  13. Which of the following conjugate bases does not react with water to produce OH?

    1. CO32–
    2. F
    3. CH3COO
    4. NO2
    5. I

    Solution


  14. Which salt, when dissolved in water, will lead to a basic solution?

    1. KF
    2. NaCl
    3. NH4Cl
    4. LiNO3
    5. none of these

    Solution


  15. Small, high-charge metal ions such as Al3+ and Fe3+ form what kind of solution when dissolved in water?

    1. acidic
    2. basic
    3. neutral

    Solution


  16. A 0.300 M HF aqueous solution is made (at 25 °C). What is the pH? Ka = 7.2 × 10–4

    1. 1.83
    2. 2.48
    3. 2.93
    4. 3.15
    5. 7.49

    Solution


  17. What is the pOH of an aqueous solution containing 0.040 M HI (at 25 °C)?

    1. 1.40
    2. 3.24
    3. 7.68
    4. 8.43
    5. 12.6

    Solution


  18. What is the pH of a 0.05 M Ca(OH)2 aqueous solution (at 25 °C)?

    1. 6
    2. 8
    3. 10
    4. 12
    5. 13

    Solution


  19. The equilibrium constant, Kb, corresponds to which of the following reactions?

    1. NaCl(s) ⇌ Na+(aq) + Cl(aq)
    2. F(aq) + H2O(l) ⇌ HF(aq) + OH(aq)
    3. NH4+(aq) + H2O(l) ⇌ NH3(aq) + H3O+(aq)
    4. HI(aq) ⇌ H+(aq) + I(aq)
    5. none of these

    Solution


  20. What is the molar concentration of a 1 L Ba(OH)2 solution with a pH of 8.15 (at 25°C)? Be sure to account for the hydroxide ion contribution from water.

    1. 6.56 × 10–7
    2. 1.31 × 10–6
    3. 1.41 × 10–6
    4. 8.34 × 10–5
    5. 4.28 × 10–4

    Solution


  21. Which of the following aqueous mixtures will yield a buffer solution? (Assume all salts are soluble)

    1. 1.05 M NH3 + 1.35 M NH4Cl
    2. 0.80 M LiOH + 0.81 M LiNO3
    3. 1.43 M NaCl + 1.03 M NaOH
    4. 0.5 M HBr + 0.5 M NaBr
    5. none of these

    Solution


  22. What is the pH of a 1 L aqueous solution containing 0.02 mol HA and 0.015 mol A (at 25 °C)? Ka(HA) = 1.77 × 10–4

    1. 2.13
    2. 2.59
    3. 3.63
    4. 3.98
    5. 4.18

    Solution


  23. A titration is carried out where a strong base is added to a weak acid solution. Choose the pH that best represents where the equivalence point would be. (Assume 25 °C)

    1. 2.4
    2. 5.4
    3. 7.0
    4. 8.5
    5. 13.2

    Solution


  24. What is the pH of a 1 L buffer solution (at 25 °C) prepared from 0.15 mol of NH3 and 0.20 mol NH4I? Ka(NH4+) = 5.8 × 10–10

    1. 4.34
    2. 5.89
    3. 6.22
    4. 7.94
    5. 9.11

    Solution


  25. Which of the following Kb values (at 25 °C) represents the strongest base?

    1. 6.5 × 10–12
    2. 1.7 × 10–9
    3. 1.6 × 10–6
    4. 2.1 × 10–3
    5. 6.4 × 10–1

    Solution


  26. What is the name for a reaction where an acid reacts with a base?

    1. neutralization
    2. combination
    3. dissolution
    4. dissociation

    Solution


  27. Which equilibrium constant best corresponds with the following reaction?

    \[\mathrm{2H_2O}(l) \rightleftharpoons \mathrm{H_3O^+}(aq) + \mathrm{OH^-}(aq)\]

    1. Ka
    2. Kb
    3. Kw
    4. Ksp
    5. Kf

    Solution


  28. A titration is performed where 10.0 mL of a 0.70 M NaOH aqueous solution is added to 25.0 mL of a 0.150 M aqueous HCl solution. What is the final pH (at 25 °C)?

    1. 1.01
    2. 2.49
    3. 12.97
    4. 13.58
    5. 14.34

    Solution