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Chemistry 2080
Spring 2009
Problem Set #4

due date: Friday, February 20th at 2 pm
Name:________________
Lab TA Name:__________________ Lab Day/Time:______________________
Practice problems (not graded). Chapter 14: 11, 12, 19, 23, 25, 33, 55
also Example 145 and the associated
Practice Example A, and Example 148 and the associated Practice Examples A and B.
1)
Here are some rates that were obtained at 298.15K for the reaction:
A
+
B
–––––>
C
Initial Rate of Disappearance
of A (M/s)
[A] (M)
[B] (M)
1)
0.053
0.10
0.50
2)
0.127
0.20
0.30
3)
1.02
0.40
0.60
4)
0.254
0.20
0.60
5)
0.509
0.40
0.30
The concentrations of A and B given above are the starting concentrations.
(a)
Determine the overall order
of the reaction.
We will assume that the rate of the reaction can be expressed as:
Rate
=
k[A]
x
[B]
y
To solve for x, we can compare experiments (2) and (5):
In these two runs, the initial concentration of B is fixed at 0.30 M, but [A] is 0.20 M in (2) and
0.40 M in (5) (i.e. twice as much). However, the rate increased by a factor of 4.0, so x = 2.
Similarly, if we compare experiments (2) and (4), [A] is fixed at 0.20 M, while [B] is 0.30
M in (2) but doubled to 0.60 M in (4). The rate increased by a factor of 2.0, so y =1.
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 Spring '07
 DAVIS,F
 Chemistry

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