4th quarter review Honors Chemistry
Unit 16 equilibrium
1. The equilibrium equation for the Haber process at 500 °C is
N2 + 3H2


2NH3 + heat
If heat is added in the above equilibrium mixture at constant pressure, then the concentration of
(A)
nitrogen decreases.
(B)
hydrogen decreases.
(C)
ammonia increases.
(D)
ammonia decreases.
(E)
ammonia remains constant.
2. The statement represents a chemical reaction at equilibrium.
A+B


C + D + heat.
The yield of substance D is increased by
(A)
removing substance A.
(B)
removing substance B.
(C)
removing substance C.
(D)
raising the temperature.
(E)
adding a catalyst to the mixture.
3. In the reaction, represented by the equation
H2F2 + energy
which set of conditions favors the formation of HF?
(A)
low temperature and high pressure
(B)
low temperature and low pressure
(C)
high temperature and high pressure
(D)
high temperature and low pressure
(E)
addition of water to the reaction mixture


2HF
4. Sulfur dioxide gas and oxygen gas react in a closed system and form sulfur trioxide gas. The reaction is represented by
the equation
2SO2 + O2 
 2SO3 + 184 kJ
The concentration of sulfur trioxide may be increased by
(A)
decreasing the pressure of the system at constant temperature.
(B)
increasing the pressure of the system at constant temperature.
(C)
decreasing the concentration of oxygen.
(D)
increasing the temperature of the system at constant pressure.
(E)
decreasing the concentration of sulfur dioxide.
5. Note the equation:
3–
–
AgCl(s) + 2S2O32–(aq) 
 Ag(S2O3)2 (aq) + Cl (aq)
If more S2O32–(aq) is added to the system at equilibrium, the
(A)
amount of AgCl(s) increases.
(B)
system cannot achieve equilibrium.
(C)
rate of forward reaction decreases.
(D)
concentration of Cl–(aq) increases.
(E)
concentration of Ag(S2O3)23–(aq) decreases
N2(g) + 3H2(g) 
 2NH3(g) + 100 kJ
6.
Which change will increase the equilibrium concentration of ammonia, NH3?
(A)
a decrease in the total pressure
(B)
a decrease in the concentration of H2(g)
(C)
a decrease in the temperature of the reaction chamber
(D)
an increase in the volume of the reaction chamber
7. In the equilibrium reaction
+
–
AgCl(s) + 2NH3(aq) 
 Ag(NH3)2 (aq) + Cl (aq)
an increase in the concentration of Cl–(aq) causes
(A)
AgCl(s) to decompose.
(B)
Ag(NH3)2+(aq) to form.
(C)
AgCl(s) to precipitate.
(D)
the NH3(aq) concentration to decrease.
8. Which change to this system at equilibrium will increase the concentration of Br2(g)?
4HBr(g) + O2(g) 
 2H2O(g) + 2Br2(g)
H = –276 kJ
(A)
an increase in pressure
(B)
an increase in temperature
(C)
the removal of oxygen, O2
(D)
the addition of water vapor, H2O(g)
9. Consider the equation:
CO2 + H2


CO + H2O
All substances are gaseous. What is the expression for the equilibrium constant?
(A)
[CO] [H2O]
[CO2] [H2]
(D)
[H2] [CO]
[CO2] [H2O]
(B)
[CO2] [H2O]
[CO] [H2]
(E)
[CO]
[CO2] [H2]
(C)
[CO2] [CO]
[H2] [H2O]
10. Which equation has this expression for its equilibrium constant?
Keq =
(A)
4+
Ni2+(aq) + Co2+(aq) 
 NiCo (aq)
(B)
4+
Ni2+(aq) + Co2+(aq) 
 NiCo (s)
(C)
2+
Ni(s) + Co2+(aq) 
 Ni (aq) + Co(s)
(D)
2+
Ni2+(aq) + Co(s) 
 Ni(s) + Co (aq)
[Ni2+(aq)]
[Co2+(aq)]
11. What is the expression for the dissociation constant for acetic acid, CH3COOH?
(A)
[H+] [CH3COO–] [CH3COOH]
(B)
[H4+] [C2O2–] [CH3COOH]
(C)
[H+] [CH3COO–]
[CH3COOH]
(D)
[CH3COOH]
[H+] [CH3COO–]
12. Given the equilibrium system
X(g) + 2Y(g) 
 XY2(g) + energy
which is the correct expression for the equilibrium constant, K?
(A)
K=
[XY2]
[X] [Y]2
(C)
K=
[X] [Y]2
[XY2]
(B)
K=
[XY2]
[X] [2Y]
(D)
K=
[X] [2Y]
[XY2]
13. Consider the system:
2CO(g) + O2(g) 
 2CO2(g)
Species
[CO]
[O2]
[CO2]
Equilibrium Concentration
2.0
1.0
16
What is the value of the equilibrium constant, Keq?
(A)
8.0
(B)
32
(C)
64
(D)
128
14. A mixture of gases is placed in a one liter cylinder. The gases react according to the equation:
CO(g) + Br2(g) 
 COBr2(g)
At equilibrium, the cylinder contains 1.0 mol of CO, 1.0 mol of Br2, and 2.0 mol of COBr2. What is the value of
the equilibrium constant for the reaction?
(A)
1.0
(B)
2.0
(C)
0.5
(D)
4.0
15. Consider this reversible reaction involving substance A and substance B:
A


2B
Keq = 9.0 mol·L–1
At equilibrium, the concentration of substance A is 1.0 mol·L–1. What is the concentration of the substance B?
(A)
9.0 mol·L–1
(C)
3.0 mol·L–1
(B)
2.0 mol·L–1
(D)
4.5 mol·L–1
16. A saturated solution of silver acetate, CH3COOAg, contains 2  10–3 mol of silver ions per liter of solution. What is
the Ksp for silver acetate?
(A)
4  10–3
(D)
4  10–6
(B)
2  10–3
(E)
2  10–6
(C)
2  10–5
17. The solubility product constant, Ksp for silver bromide, AgBr, is 4.8  10–13. When equal volumes of
2.0  10–3 M AgNO3 and 2.0  10–3 M NaBr are mixed, the mixing produces
(A)
no visible precipitate.
(B)
a visible precipitate of NaNO3.
(C)
a visible precipitate of AgBr.
(D)
a visible precipitate of AgNO3
18. Consider this equation:
AgBr(s)


Ag+(aq) + Br–(aq)
A saturated solution of silver hromide, AgBr, has a silver ion concentration of 7.1  10–7 M. What is the value of
the solubility product, Ksp for silver bromide?
(A)
8.4  10–4
(C)
1.0  10–7
(B)
3.6 10–7
(D)
5.0  10–13
19. Given the solubility product constants, Ksp, for some silver salts:
SaltKsp at 20 °C
Silver acetate, AgC2H3O2
Silver bromate, AgBrO3
Silver bromide, AgBr
Silver chloride, AgCl
4  10–3
6  10–5
5  10–13
1.7  10–10
Which salt is most soluble in water?
(A)
AgC2H3O2
(C)
AgBr
(B)
AgBrO3
(D)
AgCl
20. Consider the equation:
2+
3–
Ca3(PO4)2(s) 
 3Ca (aq) + 2PO4 (aq)
What is the solubility product expression for calcium phosphate?
(A)
Ksp = [3Ca2+] [2PO43–]
(B)
Ksp = [Ca2+]3[PO43–]2
(C)
Ksp = [Ca2+] [PO43–]
(D)
Ksp = [Ca] [PO4]
Answer sheet Quarter 4 Review
1.
2.
3.
4.
5.
D
C
D
B
D
6. C
7. C
8. A
9. A
10. C
11.
12.
13.
14.
15.
C
A
C
B
C
16.
17.
18.
19.
20.
D
C
D
A
B