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On 03/01/2015 09:23 PM, wrote:<br>
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<p>Hi, Dr. Pounds!</p>
<p><br>
</p>
<p>I had a few questions on the lab. I was wondering what the
purpose of finding the slope of the line was and if we would
use that for any other calculations. Last lab we used it to
find k, but it seems that the values of k are the same for
each trial and therefore would cancel out to be 1 when put in
the equation. Is there a use for the slope or am I missing
something in the calculations?
</p>
<p><br>
</p>
<p>Thank you!</p>
<p><br>
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<br>
Whoa.. hold on there..<br>
<br>
<br>
<br>
So you the lab description states "However, we won't actually
measure the rate constant k. Insteas we assume that since the
concentration of reactants is the same in each trial, the measured
rate is equal to k times some constant."<br>
<br>
So you have the Arrhenius equation<br>
<br>
<img style="vertical-align: middle"
src="cid:part1.08020405.08090100@mercer.edu" alt="$k =
Ae^{-E_a/RT}$"><br>
<br>
the log of which is<br>
<br>
<img style="vertical-align: middle"
src="cid:part2.06040600.05070201@mercer.edu" alt="$\ln k = \ln A -
\frac{E_a}{R} \frac{1}{T}$"><br>
<br>
based on the statement from the lab, we are going to replace k with
rate<br>
<br>
<img style="vertical-align: middle"
src="cid:part3.05040902.04020704@mercer.edu" alt="$\ln
\mathrm{rate} = \ln A - \frac{E_a}{R} \frac{1}{T}$"><br>
<br>
If we then plot the <img style="vertical-align: middle"
src="cid:part4.01040205.00030103@mercer.edu" alt="$\ln
\mathrm{rate}$"> on the y-axis and <img style="vertical-align:
middle" src="cid:part5.09090907.06020908@mercer.edu"
alt="$\frac{1}{T}$"> on the x-axis we should get a linear
relationship with the slope equal to <img style="vertical-align:
middle" src="cid:part6.01030102.09080007@mercer.edu"
alt="$-\frac{E_a}{R}$">. So from the slope you can determine the
activation energy.<br>
<br>
Got it? <br>
<br>
<pre class="moz-signature" cols="72">\mathrm{rate}--
Andrew J. Pounds, Ph.D. (<a class="moz-txt-link-abbreviated" href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a>)
Professor of Chemistry and Computer Science
Mercer University, Macon, GA 31207 (478) 301-5627
<a class="moz-txt-link-freetext" href="http://faculty.mercer.edu/pounds_aj">http://faculty.mercer.edu/pounds_aj</a>
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