Reaction Rates
Practice Test
1.
What is the reaction order for each reactant in the following rate-law expression? Rate = k[A][B]
2
[C]
3
a.
first order for A, second order for B, first order for C
b.
first order for A, second order for B, third order for C
c.
first order for A, second order for B, second order for C
d.
first order for A, first order for B, first order for C
2.
The exponents in a rate-law expression define the __________, which describes how the rate is affected by the concentration of the reactant.
a.
specific rate constant
b.
concentration
c.
instantaneous rate
d.
reaction order
3.
When you increase the temperature of a chemical reaction, the ____________.
a.
reaction slows down
b.
reaction stops
c.
reaction speeds up
d.
reaction rate does not change
4.
How are the rate law and the order for a complex reaction determined?
a.
by experimentation
b.
by calculation
c.
by estimation
d.
by trial and error
5.
Use the data in the table to calculate the average reaction rate expressed in moles HCl produced per liter per second.
Time (s)
[H
2
] (M)
[Cl
2
] (M)
[HCl] (M)
0
0.03
0.05
0.55
10
0.005
0.025
0.05
a.
0.005 mol/(L s)
b.
0.0025 mol/(L s)
c.
0.0500 mol/(L s)
d.
0.002 mol/(L s)
6.
How much time has passed when 5 mol/L have reacted at an average rate of 0.5 mol/L·s?
a.
1.0 s
b.
10 s
c.
0.1 s
d.
100 s
7.
What is the most common experimental method for evaluating a reaction order called?
a.
method of instantaneous rates
b.
method of experimental rates
c.
method of final rates
d.
method of initial rates
8.
Automobiles use a catalytic converter made of metal to ensure complete combustion of gasoline. What type of catalyst is present in automobiles?
a.
heterogeneous catalyst
b.
solid-state catalyst
c.
ephemiral catalyst
d.
homogeneous catalyst
9.
Use the data in the table to calculate the average reaction rate expressed in moles Cl
2
consumed per liter per second.
Time (s)
[H
2
] (M)
[Cl
2
] (M)
[HCl] (M)
0
0.03
0.05
0.55
10
0.005
0.025
0.05
a.
0.0025 mol/(L s)
b.
0.003 mol/(L s)
c.
0.002 mol/(L s)
d.
0.030 mol/(L s)
10.
What is the term used to describe the minimum energy needed to form an activated complex?
a.
kinetic energy
b.
potential energy
c.
activation energy
d.
temperature
11.
What happens to the activation energy of the reaction when a catalyst is present?
a.
The activation energy does not change.
b.
The activation energy decreases.
c.
The reaction stops.
d.
The activation energy increases.
12.
What are the units that generally express a reaction rate?
a.
liters per mole per second
b.
seconds per mole per liter
c.
seconds per liter per mole
d.
moles per liter per second
13.
What quantity is defined by the change in concentration of a component in a chemical reaction divided by the change in time of the reaction?
a.
catalyst
b.
specific rate constant
c.
rate order
d.
instantaneous rate
14.
What is the slowest of the elementary steps in a complex reaction called?
a.
fast step
b.
mechanism
c.
propagating step
d.
rate-limiting step
15.
What is the name given to a catalyst that exists in the same physical state as the reaction being catalyzed?
a.
heterogeneous catalyst
b.
homogeneous catalyst
c.
ephemiral catalyst
d.
solid-state catalyst
16.
What will happen when you decrease the surface area of a reactant?
a.
The reaction speeds up.
b.
The reaction slows down.
c.
The reaction rate does not change.
d.
The reaction stops.
17.
What is the term given to a temporary arrangement of atoms that may produce either products or reactants?
a.
activation energy
b.
reactant
c.
transition state
d.
collision
18.
The rate law for the reaction between nitrogen monoxide and hydrogen is Rate = k[NO
2
]2[H
2
]. What happens to the rate if the concentration of nitrogen doubles?
a.
The rate triples.
b.
The rate quadruples.
c.
The rate doubles.
d.
The rate is reduced by half.
19.
What is the instantaneous rate for a reaction that is second order in A and first order in B when [A] = 2
M
and [B] = 3
M
? The specific rate constant for the reaction is 0.1
M
-2s-1.
a.
0.012
M
/s
b.
12
M
/s
c.
1.2
M
/s
d.
0.12
M
/s
20.
What are the individual steps in a complex reaction known as?
a.
complex steps
b.
rate-determining steps
c.
intermediate steps
d.
elementary steps
