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<div class="moz-cite-prefix">On 9/26/22 17:31, wrote:<br>
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<blockquote type="cite"
cite="mid:e1954982360943d38d1948336b6f4c7d@SA1PR01MB6528.prod.exchangelabs.com">
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
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Dear Dr. Pounds,</div>
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<br>
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
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I'm confused about how to solve question 3.22, Part B. I've used
equation 3.12 from the textbook, but I'm still getting it wrong.
Am I using the wrong formula?</div>
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<br>
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Sincerely,</div>
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<p><font face="serif">So in part A you found the standard entropy
for the reaction. In part B you are going to need to find the
change in the entropy at the higher temperature - assuming that
the heat capacities don't change. So compute the change in the
heat capacity for the reaction just like you would compute the
change in a state function (products minus reactants, weighted
by their stoichiometric coefficients). Call</font></p>
<p><font face="serif">that quantity <math
xmlns="http://www.w3.org/1998/Math/MathML"><semantics><msub><mi>C</mi><mrow><mi>p</mi><mo>,</mo><mi>r</mi><mi></mi><mi></mi></mrow></msub><annotation
encoding="TeX">C_{p,RXN}</annotation></semantics></math> <br>
</font></p>
<p><font face="serif"><br>
</font></p>
<p>Now, using the equation 3.12 and the heat capacity from part A,</p>
<p><br>
</p>
<p><math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi
mathvariant="normal">Δ</mi><msub><mi>S</mi><mi>r</mi></msub><mo>=</mo><mi
mathvariant="normal">Δ</mi><msubsup><mi>S</mi><mi>r</mi><mo>∘</mo></msubsup><mo>+</mo><msubsup><mo>∫</mo><msub><mi>T</mi><mn>1</mn></msub><msub><mi>T</mi><mn>2</mn></msub></msubsup><mfrac><msub><mi>C</mi><mrow><mi>p</mi><mo>,</mo><mi>r</mi></mrow></msub><mi>T</mi></mfrac><mi>d</mi><mi>T</mi></mrow><annotation
encoding="TeX">\Delta S_r = \Delta
S_r^{\circ}+\int_{T_1}^{T_2}\frac{C_{p,r}}{T}dT
</annotation></semantics></math>where
<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><msub><mi>T</mi><mn>1</mn></msub><annotation
encoding="TeX">T_1</annotation></semantics></math> is 298 K
and
<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><msub><mi>T</mi><mn>2</mn></msub><annotation
encoding="TeX">T_2</annotation></semantics></math> is the
temperature for where you want to compute the entropy change.</p>
<p><br>
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<div class="moz-signature">-- <br>
<b><i>Andrew J. Pounds, Ph.D.</i></b><br>
<i>Professor of Chemistry and Computer Science</i><br>
<i>Director of the Computational Science Program</i><br>
<i>Mercer University, Macon, GA 31207 (478) 301-5627</i></div>
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