AP Chem Unit 12 HW Packet
Name: __________________________
_____ 95 pts
1. (5pts) The average rate of disappearance of ozone in the reaction 2O 3 (g)  3O 2 (g)
is found to be 8.85 × 10-3 atm over a certain interval of time. What is the rate of
appearance of O2 during this interval?
2. (5pts) The balanced equation for the reaction of bromate ion with bromide ion in
acidic solution is given by:
BrO3- + 5Br- + 6H+  3Br2 + 3H2O
At a particular instant in time, the value of -[Br-]/t is 2.0 × 10-3 mol/L s. What is
the value of [Br2]/t in the same units?
1
3. (10pts) For a reaction in which A and B react to form C, the following initial rate
data were obtained:
[A]
[B]
Initial Rate of
Formation of C
(mol/L)
(mol/L)
(mol/L·s)
0.10
0.10
1.00
0.10
0.20
4.00
0.20
0.20
8.00
What is the rate law?
A)
Rate = k[A][B]
D)
Rate = k[A]2[B]2
B)
Rate = k[A]2[B]
E)
Rate = k[A]3
C)
Rate = k[A][B]2
Justification:
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4. (10pts) Tabulated below are initial rate data for the reaction
2Fe(CN)63– + 2I–  2Fe(CN)64– + I2
Initial
Run
[Fe(CN)63–]0
[I–]0
[Fe(CN)64–]0
[I2]0
Rate (M/s)
1
0.01
0.01
0.01
0.01
1 × 10–5
2
0.01
0.02
0.01
0.01
2 × 10–5
3
0.02
0.02
0.01
0.01
8 × 10–5
4
0.02
0.02
0.02
0.01
8 × 10–5
5
0.02
0.02
0.02
0.02
8 × 10–5
The experimental rate law is:
A)
  I2 
t
B)
  I2 
t
C)
  I2 
t
D)
  I2 
t
E)
  I2 
t
= k[Fe(CN)63–]2[I–]2[Fe(CN)64–]2[I2]
= k[Fe(CN)63–]2[I–][Fe(CN)64–][I2]
= k[Fe(CN)63–)]2[I–]
= k[Fe(CN)63–][I–]2
= k[Fe(CN)63–][I–] [Fe(CN)64–]
Justification:
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5. (10pts) The reaction of (CH3)3CBr with hydroxide ion proceeds with the formation
of (CH3)3COH.
(CH3)3CBr(aq) + OH–(aq)  (CH3)3COH(aq) + Br–(aq)
The following data were obtained at 55C.
[(CH3)3CBr]0
[OH–]0
Inital Rate
Exp.
(mol/L)
(mol/L)
(mol/L)
1
0.10
0.10
1.0  10-3
2
0.20
0.10
2.0  10-3
3
0.10
0.20
1.0  10-3
4
0.30
0.20
?
What will the initial rate (in mol/L·s) be in Experiment 4?
A) 3.0 × 10–3 B) 6.0 × 10–3 C) 9.0 × 10–3 D) 18 × 10–3 E) none of these
Work:
6. (5pts) The reaction 2NO  N2 + O2 has the following rate law:

[ NO]
 2k[NO]2 .
t
After a period of 2.9 × 103 s, the concentration of NO falls from an initial value of
2.8  10-3 mol/L to 2.0  10-3 mol/L. What is the rate constant, k?
Work:
4
The following questions refer to the gas-phase decomposition of ethylene chloride.
C2H5Cl  products
Experiment shows that the decomposition is first order.
The following data show kinetics information for this reaction: SHOW WORK.
Time (s)
ln [C2H5Cl] (M)
1.0
–1.625
2.0
–1.735
7. (5pts) What is the rate constant for this decomposition?
A) 0.29/s B) 0.35/s C) 0.11/s D) 0.02/s E) 0.22/s
8. (5pts) What was the initial concentration of the ethylene chloride?
A) 0.29 M B) 0.35 M C) 0.11 M D) 0.02 M E) 0.22 M
9. (5pts) What would the concentration be after 5.0 seconds?
A) 0.13 M B) 0.08 M C) 0.02 M D) 0.19 M E) 0.12 M
10. (5pts) What is the time to half-life?
A) 0.7 s B) 1.3 s C) 8.9 s D) 6.3 s E) 2.2 s
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11. (5pts) Determine the molecularity of the following elementary reaction: O3  O2 +
O.
A)
unimolecular
B)
bimolecular
C)
termolecular
D)
quadmolecular
E)
the molecularity cannot be determined
Justification:
12. (5pts) The decomposition of ozone may occur through the two-step mechanism
shown:
step 1
O3  O2 + O
step 2
O3 + O  2O2
The oxygen atom is considered to be a(n)
A)
reactant
D)
reaction intermediate
B)
product
E)
activated complex
C)
catalyst
Justification:
6
13. (5pts) The reaction
2A + B  C
has the following proposed mechanism:
Step 1: A + B
equilibrium)
D (fast
Step 2:
D+BE
Step 3:
E+AC+B
If step 2 is the rate-determining step, then the rate of formation of C should equal:
A) k[A] B) k[A]2[B] C) k[A]2[B]2 D) k[A][B] E) k[A][B]2
Justification:
14. (5pts) What would happen if the kinetic energy of the reactants was not enough to
provide the needed activation energy?
A)
The products would be produced at a lower energy state.
B)
The rate of the reaction would tend to increase.
C)
The activated complex would convert into products.
D)
The reactants would continue to exist in their present form.
E)
The products would form at an unstable energy state.
Justification:
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15 (5pts) The reaction 2H2O2  2H2O + O2 has the following mechanism:
H2O2 + I–  H2O + IO–
H2O2 + IO–  H2O + O2 + I–
The catalyst in the reaction is:
A) H2O B) I– C) H2O2 D) IO–
Justification:
A reaction represented by the equation was studied at a specific temperature and the
following data were collected: (Pressure is a direct result of concentration)
3O2 (g)  2O3 (g)
time (seconds)
Total pressure (atm)
0
1.000
46.89
0.9500
98.82
0.9033
137.9
0.8733
200.0
0.8333
286.9
0.7900
337.9
0.7700
511.3
0.7233
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16. (10pts) What is the rate law for this reaction?
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