1
Chem 1110 Practice Exam 3
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. The equili
ium constant for the formation of calcium ca
onate from the ions in solution is
2.2 × 108 according to the reaction:
Ca2+(aq) + CO32 –(aq) CaCO3(s)
What is the value of the equili
ium constant for the reverse of this reaction?
a. the same, 2.2 × 108 d. 4.5 × 10– 9
. –2.2 × 108 e. 4.5 × 109
c. 2.2 × 10– 8
2. The equili
ium constants for the two reactions are known:
Mm+ + 4L– [ML4]m–4 XXXXXXXXXXKa
HL H+ + L– XXXXXXXXXXK
What must be the value of the equili
ium constant, Koverall for the following overall reaction?
Mm+ + 4HL [ML4]m–4 + 4H+ XXXXXXXXXXKoverall
a. KaKb d. KaKb4
. Ka + 4Kb e. KaKb1/4
c. Ka + Kb4
3. Dry ice (solid ca
on dioxide) is placed in a sealed container. It sublimes to produce ca
on dioxide gas and
eaches equili
ium at a given temperature. If the amount of dry ice in the container is doubled, then
________.
CO2(s) CO2(g)
a. the amount of CO2(g) would double.
. the amount of CO2(g) would increase but not double.
c. the partial pressure of CO2(g) would increase.
d. the amount of CO2(g) would not change.
e. the equili
ium amount of CO2(s) would be less.
4. Solid mercury(II) oxide decomposes when heated to produce liquid mercury and oxygen.
2HgO(s) 2Hg(l) + O2(g)
An amount of mercury(II) oxide is placed in a vessel at a particular temperature and allowed to reach
equili
ium. How could the amount of liquid mercury in the vessel be increased?
I. Adding more mercury(II) oxide.
II. Removing some oxygen.
III. Increasing the volume of the vessel.
a. I only d. I and II
. II only e. II and III
c. III only
2
5. Increasing the temperature of an exothermic reaction results in ________
a. more products and fewer reactants.
. more reactants and fewer products.
c. more reactants and products.
d. fewer reactants and products.
e. no change in the quantities of reactants and products.
6. In the Brønsted–Lowry definition of acids and bases, an acid ________
a. is a proton donor. d.
eaks stable hydrogen bonds.
. is a proton acceptor. e. co
odes metals.
c. forms stable hydrogen bonds.
7. Which of the following is the conjugate acid of the hydrogen phosphate ion, HPO42 –?
a. H3PO4 d. PO43 –
. H2PO4– e. H3O+
c. HPO42 –
8. In the following reaction in aqueous solution, the acid reactant is ________, and its conjugate base product is
________.
CH3NH2 + HSO4– CH3NH3+ + SO42 –
a. CH3NH2; CH3NH3+ d. HSO4–; SO42 –
. CH3NH2; SO42 – e. HSO4–; H3O+
c. HSO4–; CH3NH3+
9. The base ionization constant Kb describes which of the following reactions for a weak base, B, in aqueous
solution?
a. B + H+ BH+ d. B + OH– BH– + O2 –
. B + H3O+ BH+ + H2O e. BH+ + OH– B + H2O
c. B + H2O BH+ + OH–
10. Solutions of each of the hypothetical acids in the following table are prepared with an initial concentration of
0.100 M. Which of the four solutions will have the lowest pH and be most acidic?
Acid pKa
HA 4.00
HB 7.00
HC 10.00
HD 11.00
a. HA
. HB
c. HC
d. HD
e. All will have the same pH because the concentrations are the same.
11. Pure water at any temperature has ________
a. a pH less than 7. d. pH = 7.
. a pOH more than 7. e. no hydronium ions in it.
c. [H3O+] = [OH–].
3
12. The pH of a popular soft drink is 3.4; what is its hydronium ion concentration?
a. 5.0 × 10– 4 M d. 1.0 × 10– 7 M
. 4.0 × 10– 4 M e. 5.0 × 10– 5 M
c. 2.5 × 103 M
13. A cup of coffee has a hydroxide ion concentration of 1.0 × 10–10 M. What is the pH of this coffee?
a. 1.0 × 10– 4 d. 7
. 4 e. –10
c. 10
14. Identify the weakest and strongest acids in the group below. The weakest acid is listed first in the responses.
H2O, H2S, H2Se
a. H2Se < H2S d. H2O < H2Se
. H2Se < H2O e. H2O < H2S
c. H2S < H2Se
15. The pH of an aqueous sodium fluoride (NaF) solution is ________ because ________
a. 7; sodium fluoride is a simple salt.
. above 7; fluoride is a weak base.
c. below 7; fluoride reacts with water to make hydrofluoric acid.
d. about 7; fluoride is a weak base, but produces hydrofluoric acid, and these two
neutralize one another.
e. 0; sodium fluoride is a salt, not an acid or a base.
16. The stronger the acid, ________
a. the stronger its conjugate base.
. the weaker its conjugate base.
c. the more concentrated the acid.
d. the less concentrated the conjugate base.
e. the more concentrated the conjugate base.
ID: A
1
Chem 1110 Practice Exam 3
Answer Section
MULTIPLE CHOICE
1. D
2. D
3. D
4. E
5. B
6. A
7. B
8. D
9. C
10. A
11. C
12. B
13. B
14. D
15. B
16. B