Chemical Equilibrium
Practice Test
1.
For the reaction, H
2
(g) + Cl
2
(g) → 2HCl(g) + heat, what will be the effect on the equilibrium constant,
K
eq
, if the pressure of the vessel is decreased at constant temperature?
a.
K
eq
increases
b.
K
eq
decreases
c.
The question cannot be answered without knowing the initial value of
K
eq
.
d.
K
eq
does not change
2.
What is the equilibrium constant expression for the following reaction?
H
2
+ I
2
‹–› 2HI
a.
K
eq
= [2HI]/ /[H
2
][I
2
]
b.
K
eq
= [H
2
][I
2
]/ [HI]
2
c.
K
eq
= [HI]
2
/[H]
2
[I]
2
d.
K
eq
= [HI]
2
/[H
2
][I
2
]
3.
How many grams of MgF
2
will dissolve in 150 mL of 0.100
M
NaF solution? Ksp for MgF
2
is 6.4 x 10
-9
.
a.
4.1 x 10
-6
g
b.
6.0 x 10
-6
g
c.
6.4 x 10
-7
g
d.
1.0 x 10
-5
g
4.
Which of the following would force the forward reaction to completion?
CaCO
3
(s) + 2H
3
O
+
(aq) → Ca
2+
(aq) + 3H
2
O(l) + CO
2
(g)
a.
add CO
2
to the mixture
b.
conduct the experiment in an open container
c.
add base to neutralize the H
3
O
+
d.
add more Ca
2+
to the mixture
5.
When Δ G is zero, ______________.
a.
the reaction is at equilibrium
b.
the reaction is not spontaneous
c.
the reaction is spontaneous
d.
the reaction has no energy
6.
If NaCl is added to a 0.010M solution of AgNO
3
in water at 25°C, what will be [Cl
-
] when precipitation of AgCl begins? The Ksp for AgCl is 1.8 x 10
-10
.
a.
1.8 x 10
-8
M
b.
1.8 x 10
-12
M
c.
1.3 x 10
-6
M
d.
1.0 x 10
-10
M
7.
For the reaction, 2NOCl(g) +75 kJ → 2NO(g) + Cl
2
(g), which of the following will shift the reaction to the left?
a.
add a catalyst
b.
decrease the volume of the container
c.
heat the reaction vessel
d.
add more NOCl
8.
Which of the solubility product expressions is incorrect?
a.
K
sp
(Sb
2
S
3
) = [Sb
2+
]
3
[S
3-
]
2
b.
K
sp
(Ag
2
S) = [Ag
+
]
2
[S
2-
]
c.
K
sp
(CuS) = [Cu
2+
][S
2-
]
d.
K
sp
(CaF
2
) = [Ca
2+
][F
-
]
2
9.
The molar solubility for BaCO
3
is 9.0 x 10
-5
M
at 25°C. What is the solubility product constant,
K
sp
, for BaCO
3
?
a.
4.0 x 10
-15
b.
8.1 x 10
-9
c.
5.3 x 10
-12
d.
1.2 x 10
-8
10.
The value of the
K
sp
for SrSO
4
is 2.8 x 10
-7
. What is the molar solubility of SrSO
4
?
a.
5.7 x 10
-3
M
b.
7.6 x 10
-7
M
c.
5.3 x 10
-4
M
d.
5.8 x 10
-13
M
11.
For the gas phase reaction, SO
2
(g) + ½O
2
(g) → SO
3
(g), ΔH° = -1.6 × 102 kJ for the forward reaction. To increase the yield of SO
3
, the reaction should be run at ________.
a.
high pressure and high temperature
b.
low pressure and low temperature
c.
high pressure and low temperature
d.
low pressure and high temperature
12.
When will the least time be required for a reaction to reach equilibrium?
a.
K
eq
is very small
b.
K
eq
is very large
c.
cannot tell because the time to reach equilibrium does not depend on
K
eq
d.
K
eq
is approximately 1.00
13.
For the reaction, 2SO
2
(g) + O
2
(g) → 2SO
3
(g) at equilibrium, what will be the effect on the net amount of SO
3
present if the volume of the container is increased?
a.
The concentration of SO
3
will increase.
b.
The concentration of SO
3
will decrease.
c.
The concentration of SO
3
will remain the same.
d.
This question cannot be answered without knowing the value of Keq.
14.
What is the equilibrium constant expression for the following reaction?
2NH
4
NO
3
(s) → 2NH
3
(g) + 2NO(g) + H
2
(g) + 2O
2
(g)
a.
K
eq
= [NH
3
][NO][H
2
][O2]
b.
K
eq
= ([NH
3
][NO][H
2
][O2])/[NH
4
NO
3
]
c.
K
eq
= [NH
3
]
2
[NO]
2
[H
2
][O2]
2
d.
K
eq
= ([NH
3
]
2
[NO]
2
[H
2
][O2]
2
)/[NH
4
NO
3
]
2
15.
What is the equilibrium constant expression for the following reaction?
4NH
3
(g) + 5O
2
(g) → 4NO(g) + 6H
2
O(g)
a.
K
eq
= [NO]
2
[H
4
O]
6
/[NH
3
]
4
[O
2
]
5
b.
K
eq
= [NO]
4
/[NH
3
][O
2
]
c.
K
eq
= [NH
3
]
4
[O
2
]
5
/[NO]
4
[H
2
O]
6
d.
K
eq
= [NH
3
] [O
2
]/[NO] [H
2
O]
