Download Kinetics MC Questions

Kinetics Worksheet Multiple Choice
1.
Use the table of data shown below to calculate the average rate of the reaction
between 10 sec and 20 sec.
A B
time (sec)
0
5
10
15
20
[A] mol/L
0.20
0.14
0.10
0.071
0.050
a.
d.
0.005 M/sec
200 M/sec
b.
e.
0.008 M/sec
0.05 M/sec
c.
0.006 M/sec
2.
Consider the combustion of Hydrogen gas : 2H2(g) + O2(g) 2H2O(g)
If hydrogen is burning at the rate of 4.6 mol s-1, what are the rates of consumption of
oxygen and formation of water vapor?
a.
b.
c.
d.
e.
-4.6 mol s-1 (O2) and +4.6 mol s-1 (H2O)
-4.6 mol s-1 (O2) and -4.6 mol s-1 (H2O)
-2.3 mol s-1 (O2) and +4.6 mol s-1 (H2O)
-2.3 mol s-1 (O2) and +2.3 mol s-1 (H2O)
-2.3 mol s-1 (O2) and -4.6 mol s-1 (H2O)
3.
If the reaction 2A + 3D products is first-order in A and second-order in D, then the
rate law will have the form: Rate =
a.
d.
k[A][D]2
k[A]2[D]3
b.
e.
k[A][D]
k[A]2[D]
c.
k[A]2[D]2
4.
For a reaction of the type A + B + C going to products, the following observations are
made: Doubling the concentration of A doubles the rate, doubling the concentration of B
has no effect on the rate, and tripling the concentration of C increases the rate by a factor of
9. What is the rate law for the reaction?
a.
d.
Rate = k[A]2[B][C]2
Rate = k[A][B][C]
b.
e.
Rate = k[A]2[C]
Rate = k[A][C]2
c.
Rate = k[A]2[B][C]
Kinetics Worksheet Multiple Choice
5.
The following data were collected for the rate of disappearance of NO in the
reaction:
2NO(g) + O2 (g) 2NO2(g)
Initial Rate Experiment
Experiment
[NO](M)
[O2](M)
initial rate (M/s)
1
0.0126
0.0125
1.41 x 10-2
2
0.0252
0.0250
1.13 x 10-1
3
0.0252
0.0125
5.64 x 10-2
What is the rate law for the reaction and the value of the rate constant?
a.
b.
c.
d.
e.
Rate = k[NO][O2]2, k = 7.16 x 103 M-2 s-1
Rate = k[O2], k = 1.12 M-2 s-1
Rate = k[NO]2, k = 8.88 x 101 M-1 s-1
Rate = k[NO]2[O2], k = 7.11 x 103 M-2 s-1
Rate = k[NO][O2], k = 8.95 x 101 M-1 s-1
6.
In a second-order reaction the rate constant is 4.00 x 10-4 M-1 s-1. What is the
concentration of reactant after 10 min if the initial concentration is 0.800 M?
a.
d.
0.629 M
0.671 M
b.
e.
1.49 M
0.300 M
c.
0.797 M
7.
The thermal decomposition of N2O5(g) to form NO2(g) and O2(g) is a first-order
reaction. The rate constant for the reaction is 5.1 x 10-4 s-1 at 318 K. What is the half-life of
this process?
a.
d.
1.4 x 103 s
1.0 x 10-3 s
b.
e.
2.0 x 103 s
2.6 x 10-4 s
c.
3.9 x 103 s
8.
The decomposition of N2O5 in carbon tetrachloride proceeds as follows:
2N2O5 4NO2 + O2
The rate law is first-order in N2O5. At 45°C the rate constant is 6.08 x 10-4 s-1. What is the
rate of the reaction when [N2O5] = 0.100 M, and what happens to the rate when the
concentration of N2O5 is doubled to 0.200 M?
a.
6.08 x 10-3 M/s; the rate will be halved at 0.200 M
b.
6.08 x 10-5 M/s; the rate will double when the concentration of N2O5 is doubled to
0.200 M
c.
6.08 x 10-4 M/s; the rate will not change at 0.200 M
d.
6.08 x 10-5 M/s; the rate will not change
Kinetics Worksheet Multiple Choice
9.
A reaction has a rate law: rate = k[A]2. What would you plot to have the
concentration versus time data give a straight line?
a.
b.
c.
d.
e.
plot ln[A] vs time
plot 1/[A] vs time
plot log[A] vs time
plot [A] vs time
plot ln (1/[A]) vs time
10.
The decomposition of NOBr is second-order with respect to NOBr and second-order
overall. If the initial concentration of NOBr is 0.102 M and the rate constant is 25 M-1 min-1,
what is [NOBr] after 1.0 min?
a.
2.9 x 10-2 M
b.
4.0 x 10-2 M
c. 9.8 M
d. 1.4 x 10-12 M
11.
Which three factors directly affect the rate of a chemical reaction?
a.
b.
c.
d.
e.
temperature, product concentration, and container volume
temperature, reactant concentration, and catalyst
catalyst, product concentration, and container volume
temperature, pressure, and humidity
temperature, reactant concentration, and pressure
12.
Given the reaction A(g)  2B(g) and the number of moles of A at different times is
as follows,
time
0
5 min
10 min
moles A
0.100
0.085
0.070
what is the number of moles of B at 10 min if there were no moles of B initially present?
a.
d.
0.030 mol
0.060 mol
b.
e.
0.100 mol
0.140 mol
c.
0.200 mol
13.
For the gas-phase reaction H2(g) + F2(g) 2HF(g), how is the rate of disappearance of
H2 related to the rate of appearance of HF?
a.
b.
c.
d.
e.
Δ[H2]/Δt = Δ[HF]/2Δt
Δ[H2]/Δt = Δ[HF]/Δt
Δ[H2]/Δt = - Δ[HF]/2Δt
Δ[H2]/Δt = -2Δ[HF]/Δt
Δ[H2]/Δt = 2Δ[HF]/Δt
Kinetics Worksheet Multiple Choice
14.
Consider the reaction 3A2B.
The average rate of appearance of B is given by Δ[B]/Δt. How is the average rate of
appearance of B related to the average rate of disappearance of A?
a.
d.
-Δ[A]/Δt
-3Δ[A]/2Δt
b.
e.
2Δ[A]/3Δt
Δ[A]/ Δt
c.
-2Δ[A]/3Δt
15.
Consider the hydrolysis of t-butyliodide, the equation for which is
(CH3)3I + H2O (CH3)3COH + HI.
The equation governing the rate of this reaction is Rate = k[(CH3)3I]. What is the order of
each reactant and the overall order of the reaction?
a.
The order of t-butyliodide is 0, the order of water is 1, and the reaction order is 1.
b.
The order of t-butyliodide is 1, the order of water is 1, and the reaction order is 2.
c.
The order of t-butyliodide is 1, the order of water is 0, and the reaction order is 2.
d.
The order of t-butyliodide is 1, the order of water is 0, and the reaction order is 1.
e.
The order of t-butyliodide is 1, the order of water is 1, and the reaction order is 1.
16.
For first-order reactions, the rate constant, k, has the unit(s)
a.
d.
time-1
b.
(mol/L)-1 time-1
L mol-1
c.
e.
Time
time mol L-1
17.
The rate equation for the decomposition of H2O2 in the presence of I- is Rate =
k[H2O2][I-]. What are the units of the rate constant, k?
a.
d.
time-1
b.
L mol-1 time-1
L2 mol-2 time-1
e.
mol L-1 time-1
c.
L mol-1 time
18.
The reaction 2NO + 2H2 N2 + 2H2O is second-order in NO and first-order in H2.
What happens to the rate when (i) [NO] is doubled, while [H2] is fixed; (ii) [NO] is fixed,
while [H2] is doubled; (iii) both [NO] and [H2] are doubled?
a.
b.
c.
d
e.
(i) increases by a factor of 4 ; (ii) doubles ; (iii) increases by a factor of 8
(i) increases by a factor of 4 ; (ii) doubles ; (iii) increases by a factor of 4
(i) doubles ; (ii) doubles ; (iii) increases by a factor of 4
(i) increases by a factor of 4 ; (ii) doubles ; (iii) increases by a factor of 6
(i) doubles ; (ii) increases by a factor of 4 ; (iii) increases by a factor of 4
Kinetics Worksheet Multiple Choice
19.
Consider the reaction in which nitric oxide is oxidized to nitrogen dioxide,
2 NO(g) + O2(g) 2 NO2(g), for which the rate law is Rate = k[NO]2[O2]. If this reaction
takes place in a sealed vessel and the partial pressure of nitric oxide is doubled, what effect
would this have on the rate of reaction?
a.
b.
c.
d.
e.
There would be no effect on the reaction rate.
The reaction rate would double.
The reaction rate would triple.
The reaction rate would quadruple.
The reaction rate would increase by a factor of 8.
20.
Consider the reaction in which ammonia is synthesized from nitrogen and hydrogen
gases: N2(g) + 3H2(g) 2NH3(g)
How is the rate of formation of ammonia related to the rate of consumption of hydrogen?
a.
The rate of formation of ammonia is twice the rate of consumption of hydrogen.
b.
The rate of formation of ammonia is equal to the rate of consumption of hydrogen.
c.
The rate of formation of ammonia is half the rate of consumption of hydrogen.
d.
The rate of formation of ammonia is 1.5 times the rate of consumption of hydrogen.
e.
The rate of formation of ammonia is two-thirds the rate of consumption of
hydrogen.
21.
Which one of the following is incorrect for the reaction AB?
a.
The half-life is the time for 1/2 of the reactant to be consumed.
b.
The half-life of a second-order reaction depends on the initial concentration.
c.
The second-order rate constant can be found by plotting 1/[A]2 versus time, where
[A] is the concentration of reactant.
d.
The initial rates for a second-order reaction depend on the concentration of the
reactant squared.
e.
A second-order reaction does not necessarily have a 2 in front of the reactant in the
overall stoichiometric equation.
Kinetics Worksheet Multiple Choice
Answers
1. a
2.c
3. a
4. e
5. d
6. d
7. a
8. b
9. b
10. a
11. b
12. d
13. c
14. c
15. d
16. a
17. d
18. a
19. d
20. e
21. c