2. The initial rate of the reaction
PCl
5
→
PCl
3
+ Cl
2
is increased a factor of four when the concentration of PCl
5
is doubled. Therefore, the rate
a.
depends on the concentrations of PCl
3
and Cl
2
.
b.
is first order with respect to PCl
5
.
c.
is second order with respect to PCl
5
.
d.
is fourth order with respect to PCl
5
.
e.
is first order with respect to PCl
3
.
3. Consider the reaction A
→
products. Which of the following plots is consistent with a
zero-order reaction?
a.
[A] plotted against time gives a horizontal, straight line.
b.
In [A] plotted against time gives a straight line of negative slope.
c.
1/[A] plotted against time gives a straight line of positive slope.
d.
[A] plotted against time gives a straight line of negative slope.
e.
[A] plotted against time gives a curved line of negative slope, decreasing in
magnitude as time increases
4. The rate constant of a first-order reaction is 3.68 x 10
-2
s
-1
at 150°C, and the activation
energy is 71 kJ/mol. What is the value of the rate constant at 170°C?
a.
9.2 x 10
-2
s
-1
b.
3.7 x 10
-2
s
-1
c.
2.49 s
-1
d.
4.0 x 10
-2
s
-1
e.
none of the above
5. The reaction
3ClO
-
(
aq
)
→
ClO
3
-
(
aq
)
+ 2Cl
-
(
aq
) has been proposed to occur by the following mechanism.
ClO
-
(
aq
) + ClO
-
(
aq
)
→
ClO
2
-
(
aq
) + Cl
-
(
aq
) (slow)
ClO
2
-
(
aq
) + ClO
-
(
aq
)
→
ClO
3
-
(
aq
) + Cl
-
(
aq
) (fast)
Which rate law is consistent with this mechanism?
a.
rate =
k
[ClO
-
]
b.
rate =
k
[ClO
-
]
3
c.
rate =
k
[ClO
2
-
][ClO
-
]
d.
rate =
k
[ClO
-
]
2
e.
rate =
k
[Cl
-
][ClO
-
]
2
6. A catalyst speeds up a reaction by
a.
increasing the number of high-energy molecules.
b.
increasing the temperature of the molecules in the reaction.
c.
increasing the number of collisions between molecules.
d.
increasing the activation energy for the reaction.
e.
providing a new reaction pathway for molecules.