2.1.7 Practice: Reaction Rates
AP Chemistry Sem 2
Points Possible:25
Date: 2/13/2021
You will need to use a calculator and a periodic table to complete this activity.
1. Use the given data set to determine the rat
...
2.1.7 Practice: Reaction Rates
AP Chemistry Sem 2
Points Possible:25
Date: 2/13/2021
You will need to use a calculator and a periodic table to complete this activity.
1. Use the given data set to determine the rate equation, including the constant, for
each of the following reactions. Assume the reaction has the form X + Y → Z. State the
overall reaction order for each reaction.
a. (7 points)
Rate Reaction:
Rate = k [X] [Y] 2
Experiment 1 Constant (k):
Experiment
Initial Concentration
of X (mol/L)
Initial Concentration
of Y (mol/L)
Measured Initial Rate
(mol/L⋅s)
Experiment 2 Constant (k):
0.050 = k [0.1] 2 [0.4]
k = 12.5
Experiment 3 Constant (k):
0.075 = k [0.3] 2 [0.2]
k = 12.5
Overall Order: 3rd Order
b. (7 points)
Rate Reaction:
Rate = k [X] 2 [Y] 1/2
Experiment
Initial Concentration
of X (mol/L)
Initial Concentration
of Y (mol/L)
Measured Initial Rate
(mol/L⋅s)
1 0.10 0.20 2.57
2 0.10 0.10 1.25
3 0.60 0.10 1.27
Overall Order: 2-and-a-half Order
2. Answer the following questions by connecting the half-life of each first-order reaction
to the rate constant.
a. The rate constant of a first-order reaction is 2.43 × 10–2 min–1. What is the half-life of
the reaction? (2 points)
b. A first-order reaction has a rate constant of 0.547 min-1. How long will it take a
reactant concentration 0.14 M to decrease to 0.07 M? (2 points)
Answer:
t1/2 = ln(2)/(0.547)
t1/2 = 1.27 minutes
Time for reactant concentration to reduce from 0.14 M to 0.07 M:
t1/2 = 1.27 minutes
c. The half-life of a first-order reaction is 5.47 min. What is the rate constant for the
reaction? (2 points)
5.47 = ln(2)/(rate constant)
Rate constant = 0.127 min-1
d. A first-order reaction has a half-life of 0.0362 min. What is the rate constant? (2
points)
0.0362 = ln(2)/(rate constant)
Rate constant = 19.15 min-1
e. The initial concentration of the reactant X of a first-order decomposition reaction is
0.80 M. After 153 s, the concentration is 0.20 M. What is the rate law for the reaction? (3
points)
Rate law:
Rate = k [X]
Reaction constant:
t1/2 = 0.693/k
76.5 = 0.693/k
k = 0.0091
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