1. When combined in aqueous solution, which of the following makes a buffered solution?

a) a strong acid (such as HCl) and a strong base (such as NaOH)

b) a strong acid (such as HCl) and a weak acid (such as HF)

c) a weak acid (such as HF) and a weak base (such as NH3)

d) a weak acid (such as HF) and its conjugate base (such as NaF)

2. Using the Ka values listed at the end of the exam, which of the following would be best suited to make a

buffer at pH 7?

a) H3PO4(aq) and H2PO4

– c) HCN(aq) and CN–(aq)

b) H2PO4

–(aq) and HPO4

2– d) HNO2(aq) and NO2

–(aq)

3. The change in pH at the equivalence point in the titration of a strong acid with a strong base is

______the change in pH at the equivalence point in the titration of a weak acid with a

strong base.

a) smaller and less sharp than c) larger but less sharp than

b) larger and sharper than d) exactly the same as

4. Consider a sample of Al(OH)3(s) in otherwise pure water. Increasing [OH–] by adding NaOH(aq)

a) decreases the solubility of Al(OH)3 as a result of the common ion effect.

b) causes the normally soluble NaOH to precipitate.

c) causes Al(OH)3 to dissolve as a result of forming Al(OH)4

–.

d) has no effect on the solubility of Al(OH)3.

5. Which values of ÄG, Ecell, and Keq are consistent with spontaneous processes? (The values in an answer

are not necessarily consistent with each other, and you are not being asked to assess whether they are

consistent with each other.)

a. ÄG = -42 kJ; Ecell = +0.42 V; Keq = 0.42 c. ÄG = -42 kJ; Ecell = +0.42 V; Keq = 4.2

b. ÄG = +42 kJ; Ecell = -0.42 V; Keq = -0.42 d. ÄG = +42 kJ; Ecell = +0.42 V; Keq = 4.2

6. Consider the process:

H2O2(aq) + 2 H+(aq) + 3 I–(aq) → 2 H2O(l) + I3

–(aq)

What is the oxidizing agent in the process?

a. H2O2 b. H+ c. I– d. There is no oxidizing agent in this process

7. Considering the E° values given at the end of the exam, which is the strongest reducing agent?

a. Zn2+ b. Al3+ c. Zn d. Al

8. A small amount of strong base is added to a buffered solution that contains formic acid (HCOOH, a

weak acid) and sodium formate (HCOONa). Which of the following best describes the result?

a. The strong base reacts with HCOOH, and the pH increases slightly.

b. The strong base dissolves, and the pH increases substantially.

c. The strong base interacts with HCOONa, and the pH decreases slightly.

d. The pH does not change, because the pH of buffered solutions is constant.

9. If a solution contained both Zn2+(aq) and Ca2+(aq), how could we separate them?

a. Add 6 M HCl. ZnCl2(s) and Ca2+(aq) would result.

b. Add H2S and 0.2 M HCl. ZnS(s) and Ca2+(aq) would result.

c. Add (NH4)2S at pH 8. ZnS(s) and Ca2+(aq) would result.

d. These ions are in the same group and cannot be readily separated.

10. HNO3 is a strong acid. NaOH is a strong base. CH3NH2 is a weak base. Which of the following makes

a buffered solution when dissolved in 1.0 L water?

a. 1 mole NaOH and 1 mole CH3NH2

b. 0.5 mole NaOH and 1 mole CH3NH2

c. 1 mole HNO3 and 1 mole CH3NH2

d. 0.5 mole HNO3 and 1 mole CH3NH2

11. Considering the 0

red

E values given at the end of the exam, which is the strongest reducing agent?

a) Mg

b) Cu

c) Zn

d) Ag

12. Which one of the following reactions is a redox reaction?

a) K2CrO4 + BaCl2 → BaCrO4 + 2KCl

b) Pb2+ + 2Br– → PbBr2

c) Cu + S → CuS

d) None of the above

13. In a voltaic cell

a) electrons flow from the cathode to the anode

b) oxidation occurs at the cathode

c) cations move towards anode through the salt bridge

d) electrical current is generated

14. What is the oxidizing agent in the following reaction?

2MnO4

–(aq) + 5Ni(s) + 16H+(aq) → 2Mn2+(aq) + 5Ni2+(aq) + 8H2O(l)

a) MnO4

–

b) Ni

c) H+

d) There is no oxidizing agent in this reaction

15. (4 pts) A solution containing which one of the following pairs of substances will be a buffer solution?

a) NaI, HI b) KBr, HBr

c) RbCl, HCl d) CsF, HF

e) none of the above

16. (4 pts) Of the following solutions of acetic acid (CH3COOH) and sodium acetate (NaCH3COO), which

has the greatest buffering capacity?

a) 0.821 M CH3COOH & 0.217 M NaCH3COO

b) 0.821 M CH3COOH & 0.909 M NaCH3COO

c) 0.100 MCH3COOH & 0.217 M NaCH3COO

d) 0.121 M CH3COOH & 0.667 M NaCH3COO

e) They are all buffer solutions and would all have the same capacity.

17. (4 pts) What change will be caused by addition of a small amount of HCl to a solution containing

fluoride ions and hydrogen fluoride?

a) The concentration of hydronium ions will increase significantly.

b) The concentration of fluoride ions will increase as will the concentration of hydronium ions.

c) The concentration of hydrogen fluoride will decrease and the concentration of fluoride ions will

increase.

d) The concentration of fluoride ion will decrease and the concentration of hydrogen fluoride will

increase.

e) The percent of ionization of hydrogen fluoride will increase.

18. (3 pts) In the titration of 50.0 mL of 0.100 M benzoic acid (a monoprotic acid) with 50.0 mL of 0.100 M

NaOH, the properties of the solution at the equivalence point correspond exactly to the properties of

a) a 0.10 M sodium solution

b) a 0.050 M sodium benzoate solution

c) a 0.050 M sodium hydroxide solution

d) a 0.050 M benzoic acid solution