Choose the correct answer for each question.

1. Calculate the pH of a 0.14M HNO₂ solution that is 5.7% ionized.

   1.   ?    0.85
   2.   ?    1.7
   3.   ?    2.1
   4.   ?    11.9
   5.   ?    13.1

2. Which solution will have the lowest pH value?

   1.   ?    0.10M HCN
   2.   ?    0.10M HNO₃
   3.   ?    0.10M NaCl
   4.   ?    0.10M H₂CO₃
   5.   ?    0.10M NaOH

3. Which one of the following responses is true with regard to a 0.1M solution of a weak acid HA?

   1.   ?    [H⁺] > [A^-]
   2.   ?    the pH = 1.0
   3.   ?    [H⁺] < [A^-]
   4.   ?    the pH > 1.0
   5.   ?    [OH^-] > [H⁺]

4. Take a 10.0mL solution of a strong acid at pH = 2.00 and a 10.0mL solution of a strong acid at pH = 6.00 and mix them. The resulting pH will be:

   1.   ?    2.0
   2.   ?    2.3
   3.   ?    4.0
   4.   ?    6.0
   5.   ?    8.0

5. Which of the following is a basic anhydride?

   1.   ?    NO₂
   2.   ?    H₂O
   3.   ?    K₂O
   4.   ?    NaCl
   5.   ?    SO₂

6. Calculate the percent ionization of 0.020M CH₃COOH (acetic acid). K_a = 1.8x10^-5

   1.   ?    6.0x10^-4%
   2.   ?    0.03%
   3.   ?    0.09%
   4.   ?    2.5%
   5.   ?    3.0%

7. The pH of a 0.25M weak monoprotic acid (HA) soluton is 3.50. What is the K_a value for this acid?

   1.   ?    7.1x10^-4
   2.   ?    1.0x10^-7
   3.   ?    1.3x10^-3
   4.   ?    4.0x10^-7
   5.   ?    1.0x10⁷

8. What is the pH of a 0.20M solution of NH₄Cl? Given K_b(NH₃) = 1.8x10^-5

   1.   ?    3.74
   2.   ?    4.98
   3.   ?    6.53
   4.   ?    9.02
   5.   ?    10.25

9. Calculate the pH of a buffer solution which contains 0.25M benzoic acid (C₆H₅CO₂H) and 0.15M sodium benzoate (NaC₆H₅CO₂). Given K_a = 6.5x10^-5.

   1.   ?    3.97
   2.   ?    4.83
   3.   ?    4.19
   4.   ?    3.40
   5.   ?    4.41

10. You have 500.0mL of a buffer solution containing 0.20M acetic acid (CH₃COOH) and 0.30M sodium acetate (CH₃COONa). What will the pH of this solution be after the addition of 20.0mL of 1.00M NaOH solution? K_a = 1.8x10^-5

    1.   ?    4.41
    2.   ?    4.74
    3.   ?    4.56
    4.   ?    4.92
    5.   ?    5.07

11. Which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 4.6-4.8?

    1.   ?    CH₃CO₂Na/CH₃CO₂H (K_a = 1.8x10^-5)
    2.   ?    NH₃/NH₄Cl (K_a(NH₄⁺) = 5.6x10^-10)
    3.   ?    NaOCl/HOCl (K_a = 3.2x10^-8)
    4.   ?    NaNO₂/HNO₂ (K_a = 4.5x10^-4)
    5.   ?    NaCl/HCl

12. Calculate the percent ionization of cyanic acid, K_a = 2.0x10^-4, in a buffer solution that is 0.50M HCNO and 0.10M NaCNO.

    1.   ?    0.02%
    2.   ?    0.10%
    3.   ?    0.20%
    4.   ?    2.0%
    5.   ?    20%

13. A titration of an acid and base to the equivalence point results in a noticeably acidic solution. It is likely the titration involved:

    1.   ?    a strong acid and weak base.
    2.   ?    a weak acid and strong base.
    3.   ?    a weak acid and weak base (where K_a equals K_b)
    4.   ?    a strong acid and strong base.

14. Calculate the pH at the equivalence point for the titration of 0.20M HCl with 0.20M NH₃. K_b = 1.8x10^-5

    1.   ?    2.87
    2.   ?    4.98
    3.   ?    5.12
    4.   ?    7.00
    5.   ?    11.12

15. You are asked to go into the lab and prepare an acetic acid - sodium acetate buffer soluton with a pH of 4.00 +/- 0.02. What molar ratio of CH₃COOH to CH₃COONa should be used?

    1.   ?    0.18
    2.   ?    0.84
    3.   ?    1.19
    4.   ?    5.50
    5.   ?    0.10