<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Arial",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
.MsoPapDefault
{mso-style-type:export-only;
mso-margin-top-alt:auto;
mso-margin-bottom-alt:auto;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal" style="margin-bottom:12.0pt;margin-top:0in;mso-margin-bottom-alt:0in;mso-margin-top-alt:0in;mso-add-space:auto">
<span style="font-family:"Arial",sans-serif">Someone asked about 19.38b. This is and end-of-chapter exercise
<br>
and is in the MC homework. This problem states "If you heat a gas <br>
such as CO2, you will increase its degrees of translational, rotational <br>
and vibrational motions." True or False. <br>
<br>
The solutions manual states “False”. MC states this is “True”. <br>
<br>
The problem really is the question was worded poorly. The fact <br>
is the degrees of freedom (or number of them) themselves don't change. <br>
They are what they are. The added heat will be distributed between <br>
more of these motions. Remember the figure of the fraction of molecules <br>
with some kinetic energy versus kinetic energy. As the temp rises the <br>
distribution of molecules shifts to the right and spreads out. This <br>
spreading out of the distribution results in more microstates for the <br>
translational motions. This added heat causes more rotations of the <br>
molecules and inc. the vibrational motions. Adding heat causes the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">to move around more, rotate more and the bonds w/in a molecule to<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">vibrate more. This leads to more microstates. You can see pictures in<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">the solutions manual (although the picture leaves out 1 rotational motion<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">and 1 vibrational motion).
<br>
<br>
Here's a link to a discussion of vibrational degrees of freedom in general.<br>
<br>
<a href="https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Number_of_Vibrational_Modes_in_a_Molecule">https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Number_of_Vibrational_Modes_in_a_Molecule</a>
<a href="https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_%28Physical_and_Theoretical_Chemistry%29/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Number_of_Vibrational_Modes_in_a_Molecule">
<https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_%28Physical_and_Theoretical_Chemistry%29/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Number_of_Vibrational_Modes_in_a_Molecule></a>
<br>
<br>
Also, this goes to how microwave ovens work. The electromagnetic radiation <br>
produced by the microwave oven causes the molecules to rotate and the bonds <br>
to vibrate. These motions cause the molecules to heat up causing the food to <br>
be heated. The water content plays a big role in how the food heats. Here's some
<br>
links explaining this. Interestingly enough the first food cooked in a microwave
<br>
oven was popcorn. <br>
<br>
<a href="https://en.wikipedia.org/wiki/Microwave_oven">https://en.wikipedia.org/wiki/Microwave_oven</a>
<br>
<br>
<a href="https://van.physics.illinois.edu/qa/listing.php?id=821">https://van.physics.illinois.edu/qa/listing.php?id=821</a>
<br>
<br>
<a href="https://www.explainthatstuff.com/microwaveovens.html">https://www.explainthatstuff.com/microwaveovens.html</a>
<br>
<br>
Dr. Zellmer<o:p></o:p></span></p>
</div>
</body>
</html>