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Chapter Test A
Chapter: Chemical Equilibrium
In the space provided, write the letter of the term or phrase that best completes
each statement or best answers each question.
______ 1. A 15.0 mL volume of 0.0100 M Pb(NO3)2 is added to 15.0 mL of
0.0100 M NaI. A precipitate is formed, and equilibrium is established. The
Ksp equilibrium expression for the dissolution of PbI2 is
a. [Pb2][I]2.
b. [Pb][I2].
c. [Pb2][2I]2.
d. 2[Pb2][I].
______ 2. What is the ion product for the PbI2 reaction in question 1?
a. 1.00 108
b. 1.25 107
c. 1.00 106
d. 2.5 105
______ 3. What is the equilibrium expression for the following equation?
Fe(OH)3(aq) ^ Fe3(aq) 3OH(aq)
[Fe3][OH]
a. [Fe(OH)3]
[Fe3][OH]3
b. [Fe(OH)3]
[Fe(OH)3]
c. [Fe3][OH]3
[Fe(OH)3]
d. [Fe3][OH]
______ 4. In a bottle of unopened cola, the CO2 gas dissolved in the liquid is in
equilibrium with the CO2 gas above the liquid. The dissolved gas reacts
with water molecules in the cola to form carbonic acid, which also
dissociates into carbon dioxide and water. Which chemical equation(s)
best describe this equilibrium system?
a. CO2(g) ^ CO2(l)
b. CO2(g) ^ CO2(aq) and CO2(l) H2O(l) ^ H2CO3(aq)
c. CO2(g) ^ CO2(aq)
d. CO2(g) ^ CO2(aq) and CO2(aq) H2O(l) ^ H2CO3(aq)
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Chapter Test A, continued
______ 5. The Haber process, N2(g) 3H2(g) ^ 2NH3(g) 92 kJ, is operated at
temperatures of about 500°C because
a. a higher temperature would favor the products.
b. K is a maximum at 500°C.
c. the forward reaction rate is too slow at lower temperatures.
d. K is equal to 1 at 500°C.
______ 6. Which of the following would not affect the aqueous equilibrium
reaction represented by the equation below?
HNO2(aq) ^ H(aq) NO
2 (aq)
a. the addition of NaNO3(s)
b. an increase in H concentration
c. the addition of NaNO2(s)
d. a decrease in NO
2 concentration
______ 7. Consider the equilibrium system represented by the equation below.
2
H2O(l) 2CrO2
4 (aq) ^ Cr2O7 (aq) 2OH (aq)
yellow
orange
If the hydroxide ions were removed, how would the color change?
a. to darker yellow
b. to lighter orange
c. to darker orange
d. not at all
______ 8. The Fe ion present in acid mine drainage is colorless and surrounded
by water molecules. If phenanthroline (Phe) is added, the solution
turns orange as a colored complex is formed according to the equation
Fe3 H2O Phe ^ Fe3 Phe H2O. The color is commonly used
as an indicator of the Fe ion concentration. What would an increase
in color from light to dark orange indicate in this system?
a. an applied stress that shifted the equilibrium to favor the reverse
reaction
b. an applied stress that shifted the equilibrium to favor the forward
reaction
c. an increase in the rate of the reverse reaction
d. addition of water to the system
______ 9. The solubility product constant expression includes
a. a concentration of zero for undissolved salt.
b. the concentrations of dissolved and undissolved salt.
c. an exponent corresponding to the charge on each ion.
d. the concentrations of dissociated ions.
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Chapter Test A, continued
______10. In a reaction that goes nearly to completion,
a. the re-formation of reactants is much slower than the formation of
the products.
b. the rate of the reverse reaction is faster than the rate of the forward
reaction.
c. the re-formation of reactants is much faster than the rate of
formation of the products.
d. the forward reaction rate increases.
______11. Which of the following Keq expressions is correct for the formation of
ammonia, NH3, from its elements, as represented by the equation
3H2 N2 ^ 2NH3 92 kJ?
[NH3]2
a. 3
[H2] [N2]
[H2]3[N2]
b. [NH3]2
[NH3]
c. [H2][N2]
[H2][N2]
d. [NH3]
______12. When you calculate the Ksp of calcium fluoride, CaF2, if the
concentration of the F ion is 4.2 104 M, then the concentration
of the Ca2 ion is
a. 2.1 104 M.
b. 8.4 104 M.
c. 4.2 104 M.
d. 3.7 1011 M.
______13. Which of the following salts is least soluble?
a. Ag2CO3
Ksp 8.4 1012
b. Ag2CrO4
Ksp 1.1 1012
c. AgI
Ksp 1.5 1016
d. AgBr
Ksp 5.4 1013
______14. Consider the reaction represented by the equation 2NO(g) O2(g) ^
2NO2(g). If the volume of the reaction chamber is decreased, then the
a. forward reaction will be favored.
b. reverse reaction will be favored.
c. initial pressure of NO2 will decrease.
d. initial pressure of O2 will remain constant.
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Chapter Test A, continued
______15. Consider the reaction represented by the equation Ag2SO4(aq) ^
2Ag(aq) SO2
4 (aq). You can shift the equilibrium to favor the
reverse reaction by adding
a. CaCl2.
b. AgNO3.
c. Na2SO4.
d. Both (b) and (c)
______16. A chemical reaction that is at equilibrium always has
a. a high Keq value.
b. a forward reaction rate that equals the reverse reaction rate.
c. equal concentrations of reactants and products.
d. Both (a) and (b)
______ 17. Which of these is true about the chemical equation below?
reactants e products
a. The concentration of the products is greater than the concentration
of the reactants.
b. Keq of the forward reaction has a low value.
c. The reaction favors the products.
d. Keq is equal to 1.
______18. In which of the following reactions, described by the equations below,
will an increase in pressure have no effect on the equilibrium of the
system?
a. 2NO2(g) ^ N2O4(g)
b. 2NOCl(g) ^ 2NO(g) Cl2(g)
c. H2O(g) CO(g) ^ H2(g) CO2(g)
d. N2(g) 3H2(g) ^ 2NH3(g)
______19. The common-ion effect promotes
a. dissolution.
b. precipitation.
c. boiling.
d. ionization.
______20. What is the acid ionization expression for the equation
HA(aq) H2O(l) ^ H3O(aq) A(aq)?
[A][H3O]
a. [HA][H2O]
[A]
b. [HA][H2O]
[A][H3O]
c. [HA]
d. [A ][H3O][HA][H2O]
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Chapter Test A, continued
______21. The reaction represented by the equation BH(aq) H2O(l) ^
H3O(aq) B(aq) is an example of a(n)
a. cation hydrolysis reaction.
b. anion hydrolysis reaction.
c. conjugated reaction.
d. pH reaction.
______22. What is the value of Kw?
a. 1 1014
b. 1 1014
c. 1 107
d. 14 1014
______23. An example of a good buffer solution is one that contains
a. HCl and NaCl.
b. HNO2 and NaCl.
c. HNO2 and NaNO2.
d. CH3COOH and NaCl.
______24. When H3O ions are added to an aqueous solution of acetic acid,
a. the reaction forms more CH3COO.
b. the reaction forms more water.
c. the reaction forms more CH3COOH.
d. nothing happens.
______25. Which of the following is a conjugate acid-base pair in the reaction
represented by the equation below?
H2PO
4 H2O ^ H3PO4 OH
a.
b.
c.
d.
H2PO
4 and H2O
H2PO
4 and OH
H2PO4 and H3PO4
None of the above
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Modern Chemistry
168
Chapter Test
Print RESOURCE PAGE
TEACHER
24. Homogeneous reactions involve reac-
25.
26.
27.
28.
tants and products that exist in a single phase. Heterogeneous reactions
involve reactants in two different
phases.
The energy of the activated complex is
greater than the energy of the reactants and greater than the energy of
the products.
nature of reactants, surface area, temperature, concentration, presence of
catalysts
In order for a reaction to occur, the
molecules or atoms must collide with
sufficient energy to overcome the activation energy barrier. The collision
also must occur in the correct orientation, in most cases at a particular end
of a molecule or atom.
The rate law is determined from the
slowest step, called the rate-determining step because it has the slowest
rate.
29.
Energy
Activated complex
Ea
Reactants
Product
Course of reaction
1 mol Mg
24.3 g Mg
33. 0.060 g Mg 2.469
103 mol Mg
∆(mol Mg)
Average rate ∆t
2.469 103 mol Mg
25 s
9.9 105 mol/s
34. two
18 Chemical
Equilibrium,
pp. 164–173
TEST A
1.
3.
5.
7.
9.
11.
13.
15.
17.
19.
21.
23.
25.
a
b
c
c
d
a
c
d
b
b
a
c
c
2.
4.
6.
8.
10.
12.
14.
16.
18.
20.
22.
24.
c
d
a
b
a
a
d
b
c
c
a
c
TEST B
30.
Without
catalyst
Energy
Back
With
catalyst
Course of reaction
The activation energy is lower with a
catalyst than without the catalyst, but
the net energy change is the same for
both reactions.
31. R k[A]n[B]m. R is the reaction rate,
k is the specific rate constant, [A] and
[B] are the molar concentrations of
the reactants, and n and m are the
respective powers to which the concentrations are raised.
32. R k[A]2
1.
3.
5.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
a
2. b
d
4. b
b
6. c
a
basic
→ H3O(aq) OH(aq)
2H2O(l) ←
dissolved ions
dynamic
K [Ag][Cl]
common-ion effect
remains nearly constant
equal to
denominator
[NH4][OH]
K
[NH3]
exothermic
gas phase or gas state
anion hydrolysis
buffered
[H3O][A]
Ka [HA]
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233
Answer Key
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Print RESOURCE PAGE
TEACHER
23. changes in concentration, changes in
pressure, changes in temperature
24. If a product is precipitated as a solid;
if a gaseous product forms and
escapes; if a soluble product is only
slightly ionized
25. none
26. reverse reaction is favored
27. forward reaction is favored
28. neutral
29. acidic
30. basic
31. neutral
32. acidic
33. effective buffer
34. ineffective buffer
35. ineffective buffer
36. effective buffer
37. 0.20
38. 3.5
39. 1.79 103 mol/L
40. 1.2 108
41. 5.3 1017 mol/L
42. 6.0 1011; no
19 Oxidation-Reduction
Reactions, pp. 174–182
TEST A
1.
3.
5.
7.
9.
11.
13.
15.
17.
19.
21.
23.
25.
d
d
b
a
c
d
d
c
c
a
d
c
b
2.
4.
6.
8.
10.
12.
14.
16.
18.
20.
22.
24.
b
a
c
d
d
c
b
a
b
d
c
b
TEST B
1.
3.
5.
7.
9.
11.
13.
15.
b
b
d
b
b
b
b
b
2.
4.
6.
8.
10.
12.
14.
16.
a
c
d
b
d
d
b
b
17.
19.
21.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
d
18. b
d
20. d
d
22. c
a
4
water and oxygen
disproportionation
reduced
1
reduction
reduction
oxidation
2 for Ca; 4 for C; 2 for O
2 for Fe; 5 for N; 2 for O
redox
nonredox
redox
Zn(s) 3 Zn2 2e
Cl2(g) 2e 3 2Cl(g)
Zn(s) Cl2(g) 3 ZnCl2(s)
K2Cr2O7 14HCl 3
2KCl 2CrCl3 7H2O 3Cl2
20 Electrochemistry,
pp. 183–192
TEST A
1.
3.
5.
7.
9.
11.
13.
15.
17.
19.
21.
23.
25.
2.
4.
6.
8.
10.
12.
14.
16.
18.
20.
22.
24.
d
c
d
c
a
b
a
a
d
b
a
a
d
2.
a
4.
b
6.
a
8.
b
10.
cathode
electrochemistry
electric energy
anode
voltaic cell
b
b
c
d
b
b
d
c
a
d
b
b
c
d
d
a
b
c
TEST B
1.
3.
5.
7.
9.
11.
12.
13.
14.
15.
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234
Answer Key