Section 18.1
Equilibrium: A State of Dynamic Balance
Practice Test
1.
What is the equilibrium constant expression for the following reaction?
ClNO
2
+ NO ‹–› NO
2
+ ClNO
SC.A.1.4.4
a.
K
eq
=
NO
2
ClNO
/
ClNO
2
NO
b.
K
eq
=
ClNO
2
NO
/
NO
2
ClNO
c.
K
eq
=
NO
2
ClNO
/
ClNO
2
NO
d.
K
eq
=
ClNO
2
ClNO
/
NO
NO
2
Hint
2.
What is the equilibrium constant expression for the following reaction?
2SO
3
‹–› 2SO
2
+ O
2
SC.A.1.4.4
a.
K
eq
=
2SO
2
2O
/
2SO
3
b.
K
eq
=
SO
2
2
O
2
/
SO
3
2
c.
K
eq
=
SO
3
2
/
SO
2
2
O
2
d.
K
eq
= 2
SO
2
2
O
2
/2
SO
3
Hint
3.
When will the least time be required for a reaction to reach equilibrium?
SC.A.1.4.4
a.
cannot tell because the time to reach equilibrium does not depend on
K
eq
b.
K
eq
is very small
c.
K
eq
is approximately 1.00
d.
K
eq
is very large
Hint
4.
What is the equilibrium constant expression for the following reaction?
H
2
+ I
2
‹–› 2HI
SC.A.1.4.4
a.
K
eq
=
HI
2
/
H
2
I
2
b.
K
eq
=
H
2
I
2
/
HI
2
c.
K
eq
=
2HI
/ /
H
2
I
2
d.
K
eq
=
HI
2
/
H
2
I
2
Hint
5.
What is the equilibrium constant expression for the following reaction?
4NH
3
g
+5O
2
g
→ 4NO
g
+6H
2
O
g
SC.A.1.4.4
a.
K
eq
=
NO
2
H
4
O
6
/
NH
3
4
O
2
5
b.
K
eq
=
NH
3
4
O
2
5
/
NO
4
H
2
O
6
c.
K
eq
=
NH
3
O
2
/
NO
H
2
O
d.
K
eq
=
NO
4
/
NH
3
O
2
Hint
6.
Consider the following reaction in which all reactants and products are gases. 1.00 mole of A and 2.00 moles of B are placed in a 5.0—L container. After equilibrium has been established, 0.50 mole of D is present. What is the equilibrium constant for this reaction: A+ 2B → 2C+D?
SC.B.1.4.2
a.
1
b.
0.33
c.
0.15
d.
3
Hint
7.
A molecular system that is a dynamic process with two opposing reactions balancing each other is a
n
___________.
SC.A.1.4.4
a.
unreacted set of chemicals.
b.
chemical equilibrium
c.
spontaneous reaction
d.
nonspontaneous reaction
Hint
8.
What is the equilibrium constant expression for the following reaction?
PCl
5
‹–› PCl
3
+ Cl
2
SC.A.1.4.4
a.
K
eq
=
PCl
5
/
PCl
3
Cl
2
b.
K
eq
=
PCl
3
Cl
2
/
PCl
5
c.
K
eq
=
PCl
5
/
PCl
3
Cl
2
d.
K
eq
=
PCl
3
Cl
2
/
PCl
5
Hint
9.
For the reaction, 2A+B→ C+2Dat 35°C, the value of the forward rate constant,
K
f, is 3.0 × 10
-3
M
-1
s
-1
and the value of the reverse rate constant,
K
r, is 1.5 × 10
-2
M
-2
s
-1
. Calculate the value of
K
eq
for this reaction.
SC.A.1.4.4
a.
0.5
b.
2
c.
0.2
d.
5
Hint
10.
When the systemA+B↔C+D is at equilibrium, ___________.
SC.A.1.4.4
a.
both the forward and reverse reactions have stopped
b.
the forward reaction has stopped
c.
neither the forward nor the reverse reaction has stopped
d.
the reverse reaction has stopped
Hint
11.
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
SC.A.1.4.4
a.
K
eq
=
NH
3
2
NO
2
H
2
O2
2
b.
K
eq
=
NH
3
2
NO
2
H
2
O2
2
/
NH
4
NO
3
2
c.
K
eq
=
NH
3
NO
H
2
O2
/
NH
4
NO
3
d.
K
eq
=
NH
3
NO
H
2
O2
Hint
12.
When Δ G is zero, ______________.
SC.B.1.4.7
a.
the reaction is at equilibrium
b.
the reaction is not spontaneous
c.
the reaction has no energy
d.
the reaction is spontaneous
Hint
13.
What is the equilibrium constant expression for the following reaction?
N
2
+ 3H
2
‹–› 2NH
3
SC.A.1.4.4
a.
K
eq
=
N
2
3
H
2
/2
NH
3
b.
K
eq
=
NH
3
2
/
N
2
H
2
3
c.
K
eq
=
N
2
H
2
3
/
NH
3
2
d.
K
eq
= 2
NH
3
/
N
2
3
H
2
Hint
