AP Chemistry – Chapter 14 Review Packet
Multiple Choice Questions:
1.
For the stepwise dissociation of aqueous H3PO4, which of the following is NOT a
conjugate acid-base pair?
a.
b.
c.
d.
e.
2.
Name______________________________
HPO42 and PO43
H3PO4 and H2PO41
H2PO41 and HPO42
H2PO41 and PO43
H3O+1 and H2O
What is the equilibrium constant for the following reaction?
N31 + H3O+1 ↔ HN3 + H2O
The Ka value for HN3 = 1.9 x 105
a.
b.
c.
d.
e.
3.
The hydrogen sulfate (or bisulfate) ion HSO41 can act as either an acid or a base in water
solution. In which of the following equations does HSO41 act as an acid?
a.
b.
c.
d.
e.
4.
5.3 x 1010
1.9 x 109
1.9 x 105
5.3 x 104
1.9 x 109
HSO41 + H2O → H2SO4 + OH1
HSO41 + H3O+1 → SO3 + 2 H2O
HSO41 + OH1 → H2SO4 + O2
HSO41 + H2O → SO42 + H3O+1
none of these
Using the following Ka values, indicate the correct order of base strength.
HNO2
Ka = 4.0 x 104
HF
Ka = 7.2 x 104
HCN
Ka = 6.2 x 1010
a.
b.
c.
d.
e.
CN1 > NO21 > F1 > H2O > Cl1
Cl1 > H2O > F1 > NO21 > CN1
CN1 > F1 > NO21 > Cl1 > H2O
H2O > CN1 > NO21 > F1 > Cl1
none of these
5.
Which of the following is the equilibrium constant expression for the dissociation of the
weak acid HOCl?
a. K = [H+1] [OCl1]
[HOCl]
b. K = [H+1] [OCl1]
c. K =
[HOCl]____
[H+1] [OCl1]
d. K = [H+1] [O2] Cl1]
[HOCl]
e. none of these
Use the following equations for questions 6 and 7. The following three equations represent
equilibria that lie far to the right.
HNO3 (aq) + CN−1 (aq) ↔ HCN (aq) + NO3−1 (aq)
HCN (aq) + OH−1 (aq) ↔ H2O (ℓ) + CN−1 (aq)
H2O (ℓ) + CH3O−1 (aq) ↔ CH3OH (aq) + OH−1 (aq)
6.
Identify the strongest acid.
a. HCN
b. HNO3
c. H2O
d. OH−1
e. CH3OH
7.
Identify the strongest base.
a. CH3O−1
b. CH3OH
c. CN−1
d. H2O
e. NO3−1
8.
In which of the following reactions does the H2PO41 ion act as an acid?
a. H3PO4 + H2O ↔ H3O+1 + H2PO41
b. H2PO41 + H2O ↔ H3O+1 + HPO42
c. H2PO41 + OH1 ↔ H3PO4 + O2
d. The ion cannot act as an acid.
e. Two of these
9.
Which of the following is true for the dissociation of a weak acid?
a. Ka is large.
b. The equilibrium lies far to the right.
c. The equilibrium lies far to the left.
d. [H+1] >>[HA]
e. The conjugate base will be weak.
10.
Which of the following reactions is associated with the definition of Kb?
a. Zn(OH)6+2 ↔ [Zn(OH)5(OH)]+1 + H+1
b. CN1 + H+1 ↔ HCN
c. F1 + H2O ↔ HF + OH1
d. Cr+3 + 6 H2O ↔ Cr(OH2)6+3
e. none of these
11.
Use the following Ka’s to answer the question.
HAc
Ka = 1.8 x 105
H2CO3
Ka1 = 4.3 x 107
Ka2 = 5.6 x 1011
a. HAc
b. NaAc
c. Na2CO3
d. H2CO3
e. NaHCO3
12.
The conjugate acid and conjugate base of the bicarbonate ion, HCO31, are, respectively:
a. H3O+1 and OH1
b. H3O+1 and CO32
c. H2CO3 and OH1
d. H2CO3 and CO32
e. CO32 and OH1
13.
Which of the following species is present in the greatest concentration in a 0.100 M
H2SO4 solution in H2O?
a. H3O+1
b. HSO41
c. H2SO4
d. All species are in equilibrium and therefore have the same concentration.
e. SO42
14.
The sodium salt, NaA, of a weak acid is dissolved in water; no other substance is added.
Which of these statements (to a close approximation) is true?
a. [H+1] = [A1]
b. [H+1] = [OH1]
c. [A1] = [OH1]
d. [HA] = [OH1]
e. none of these
15.
The hydrogen halides (HF, HCl, HBr, and HI) are all polar molecules. The strength of
the acid each forms in water is based on which of the following?
a. the polarity of the molecule
b. the size of the molecule
c. the strength of the bond
d. two of these
e. none of these
16.
Which factor listed below is most important in determining the strength of an oxyacid?
a. the size of the molecule
b. the ability of the molecule to change atomic orientation
c. the identity of the central atom in the molecule
d. the number of oxygen atoms present in the molecule
e. none of these
For questions 17-19, use the following information.
If the following substance is dissolved in pure water, will the solution be acidic, neutral,
or basic?
a. Acidic
b. Neutral
c. Basic
17.
solid sodium nitrate
18.
solid silver chloride
19.
solid sodium carbonate
20.
As water is heated, its pH decreases. This means that
a. the water is no longer neutral.
b. the Kw value is decreasing.
c. the water has a lower [OH−1] than cooler water.
d. the dissociation of water is an endothermic process.
e. none of these
Free-Response Questions
1.
Calculate the pH of 5.00 mL of 1.5 M hydrochloric acid diluted to 100. mL.
2.
Indicate whether the following solution is acidic, basic, or neutral: [H+1] = 1.5 x 1010 M.
3.
Identify the acid, base, conjugate acid, and conjugate base in the following reaction:
NH21 (aq) + H2O (ℓ)
 NH3 (aq) +
OH1 (aq)
4.
Citric acid, H3C6H5O7, is present in citrus fruits. Calculate the pH of a 0.050 M solution
of citric acid. Explain any approximations or assumptions that you make in your
calculations. Ka1 = 3.5 x 104, Ka2 = 1.7 x 105, and Ka3 = 4.0 x 107.
5.
Identify the Lewis acid and Lewis base in the following reaction:
Fe(ClO4)3 (s) + 6 H2O (ℓ)  Fe(H2O)6+3 (aq) + 3 ClO41 (aq)
6.
At normal body temperature, 37C, Kw = 2.4 x 1014. Calculate [H+1], [OH1], pH and
pOH for a neutral aqueous solution at this temperature.
7.
Determine the nature of magnesium sulfite when dissolved in water. (Is it acidic, basic,
or neutral). Explain.
8.
Calculate the percent ionization of hydroazoic acid, HN3, in solutions of the following
concentrations: 0.400 M and 0.100 M. Ka = 1.9 x 105.
9.
Calculate the pH of a 0.050 M solution of ethylamine, C2H5NH2. Kb = 6.4 x 104.
10.
Write the balanced net ionic equation and the base-dissociation-constant expression for
the reaction of the formate ion, CHO21 (a weak base) with water.
11.
Codeine, C18H21NO3, is a weak organic base. A 5.0 x 103 M solution of codeine has a
pH of 9.95. Calculate the value of Kb for this substance.
12.
How many grams of potassium hydroxide are necessary to prepare 800. mL of a solution
of pH = 11.56?
Use the following information for questions 13-15. Acrylic acid (CH2═CHCO2H) is a
precursor for many important plastics. Ka for acrylic acid is 5.6 x 105.
13.
Calculate the pH of a 0.10 M solution of acrylic acid.
14.
Calculate the percent dissociation of a 0.10 M solution of acrylic acid.
15.
Calculate the pH of a 0.050 M solution of sodium acrylate (NaC3H3O2.)
16.
Tartaric acid is found in many plants (grapes, for example). It is partly responsible for
the dry texture of certain wines. Calculate the pH of a 0.025 M solution of tartaric acid.
(Ka1 = 1.0 x 103 and Ka2 = 4.6 x 105.) Explain any approximations that you may make.
17.
Find the pH of a 0.15 M solution of methylamine, NH2CH3. (Kb = 4.4 x 104)
18.
Calculate the pH and pOH of a 0.030 M solution of oxalic acid.
(Ka1 = 6.5 x 102 and Ka2 = 6.1 x 105.) Explain any approximations that you may make.
19.
Hemoglobin (abbreviated Hb) is a protein that is responsible for the transport of oxygen
in the blood of mammals. Each hemoglobin molecule contains four iron atoms that are
the binding sites for O2 molecules. The oxygen binding is pH dependent. The relevant
equilibrium reaction is
HbH4+4 + 4 O2 ↔ Hb(O2)4 + 4 H+1
Use LeChâtelier’s principle to answer the following:
a. What form of hemoglobin, HbH4+4 or Hb(O2)4 is favored in the lungs? What
form is favored in the cells?
b. When a person hyperventilates, the concentration of CO2 in the blood is
decreased. CO2 is a weak acid in the reaction: CO2 + H2O ↔ HCO31 + H+1
How does this affect the oxygen-binding equilibrium? How does breathing into a
paper bag help to counteract this effect?
c. When a person has suffered a cardiac arrest, injection of a sodium bicarbonate
(NaHCO3) solution is given. Why is this necessary?