AP Chem
Kinetics Test
1. Radioactive decay is a
A. First order process
B. Second order process
C. Third order process
D. Zeroth order process
E. None of these
2. Reactions with higher activation energy are
A. Slower
B. Faster
C. First order
D. Second order
E. Third order
3. The energy difference between the reactants and the transition state is
A. The free energy
B. The heat of reaction
C. The activation energy
D. The kinetic energy
E. The reaction energy
4. The slow rate of a particular chemical reaction may be attributed to which of the following?
A. A low activation energy
B. A high activation energy
C. The presence of a catalyst
D. The temperature is high
E. The concentration of the reactants is high
5. The purpose of striking a match on the side of the box is
A. To supply the free energy for the reaction
B. To supply the activation energy of the reaction
C. To supply the heat of reaction
D. To supply the kinetic energy for the reaction
E. To catalyze the reaction
6. The decomposition of ammonia to hydrogen and nitrogen is a first order reaction with a half-life of 200s at a certain temperature. How long will it take the partial pressure of ammonia to decrease from .1 atm. to .00625 atm.?
A. 200s
B. 400s
C. 800s
D. 1000s
E. 1200s
7. A reaction follows the rate law rate = k[A]. Which of the following plots gives a straight line?
A.
8. The mechanism below has been proposed for the reaction of CHCl3 with Cl2:
Step 1: Cl2 = 2Cl (fast equilibrium)
Step 2: Cl + CHCl3 = CCl3 + HCl (slow)
Step 3: CCl3 + Cl = CCl4 (fast)
Which rate law is consistent with the mechanism?
A. k[Cl2]
B. k[CHCl3] [Cl2]
C. k[CHCl3]
D. k[CHCl3]/[Cl2]
E. k[CHCl3][Cl].5
9. When the concentration of H+ is doubled for the reaction H2O2 + 2Fe3+ 2H+ = 2Fe3+ + 2H2O there is no change in the reaction rate. This indicates:
A. that H+ is a spectator ion.
B. that the rate-determining step does not involve H+
C. that H+ is a catalyst
D. that the reaction mechanism does not involve H+
E. that the rate law is first order in H+
10-14. The steps below represent a proposed mechanism for the catalyzed oxidation of CO by O3.
Step 1: NO2 + CO = NO + CO2
Step 2: NO + O3 = NO2 + O2
10. What are the overall products of the reaction?
A. CO2 and O2
B. NO and CO2
C. NO2 and O2
D. NO and O2
E. NO2 and CO2
11. What is the catalyst?
A. NO
B. NO2
C. O3
D. CO
E. O2
12. What is likely the slow step in the mechanism?
A. Step 1
B. Step 2
C. Cannot be determined
13. Increasing the concentration of which species should result in the largest increase in reaction rate?
A. NO2
B. CO
C. O3
D. None will increase the rate
E. All increase the rate equally
16. The rate constant for the radioactive decay of beryllium-11 is .049s-1. What mass of a .5g sample would remain after 28 seconds?
A. .250g
B. .125g
C. .0625g
D. .375g
E. .5g
17. Here is data for three experiments involving the production of COCl2 from CO and Cl2:
Experiment: [CO]o [Cl2]o Initial rate of reaction:
1 .2 .1 3.9
2 .1 .2 3.9
3 .2 .2 7.8
The rate law is rate=
A. k[CO]
B. k[CO][Cl2]
C. k[Cl2]
D. k[CO][Cl2]^2
E. k[CO][Cl2]
18. 2ClO2 + 2 OH- = ClO3- + ClO2- + H2O
Here is data from 3 experiments:
Experiment: [OH-]o [ClO2]o Rateo
1 .03 .02 .166
2 .06 .02 .331
3 .03 .04 .661
A. Give the order of the reaction and each reactant.
B. Give the rate law.
C. Determine the value of k. The concentrations are in M and the units for the rate is mol/Lmin.
D. Calculate the initial rate of the reaction in experiment 1.
E. The following mechanism has been proposed.
Step 1: ClO2 + ClO2 = Cl2O4
Step 2: Cl2O4 + OH- = ClO3- + HClO2
Step 3: HClO2 + OH- = ClO2- + H2O
Which step is the rate determining step? Show that this mechanism is consistent with both the rate law and the overall reaction stoichiometry.
19. Substance A forms substance B in the first order reaction A = 2B. The concentration of A falls to 20% of its original value after 120s.
A. What is the rate constant?
B. How long will it take for a sample of B to fall to 10% of its original concentration?
20. The decomposition of NH3 to N2 and H2 was studied on two surfaces.
Surface: Ea (kJ/mol)
W 163
Os 197
Without a catalyst the activation energy is 335kJ/mol.
A. Which metal is the better catalyst?
B. How many times faster is the reaction at 298K on the W surface compared to the uncatalyzed reaction?
C. The decomposition obeys the rate law rate = k[NH3]/[H2] Explain why the reaction rate has an inverse dependence on [H2].