General Chemistry Lab

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General Chemistry Lab

• Rates of Chemical Reactions, I
• The Iodination of Acetone
• Experiment 20, p.155

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Rate k acetonem I2n Hp
We want you to determine the value of m, n, and p.
Abbreviate acetone as A
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colored
colorless
We can follow the course of the reaction by
observing color changes.
Rate k Am I2n Hp
The reaction is zero order with respect to I2 (n
0). So the rate does not depend on I2 at
all, as long as I2 is not 0. In the lab, you
will make I2 the limiting reagent, present in a
large excess of acetone and H, so the of
these effectively do not change.
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The rate of the reaction is constant during its
course under these conditions, so we can vary the
rate by changing the initial A and H.
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If we double the A while holding the of
the other two constant
Rate 2 k 2Am I20 Hp
Rate 1 k Am I20 Hp
What happened to the other terms in these
equations?
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So by timing these two reactions, we can discover
the order of the reaction with respect to A
(that is, the value of m).
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Next we double the initial H while holding
the of the other two constant
Rate 2 k Am I20 2Hp
Rate 1 k Am I20 Hp
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So by timing these two reactions, we can discover
the order of the reaction with respect to H
(that is, the value of p).
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Before you arrive at chemistry lab, read and
study the introduction to Lab Exercise 20
(p.155). Then read and re-read the Experimental
Procedure on pp.157-161 until you completely
understand what you will do. Next week you will
need to do this for Lab Exercise 21 Rates of
Chemical Reactions, II. A Clock Reaction (p.165).
This ppt file is available on my web
sitehttp//www.evangel.edu/Personal/badgers/Web/