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<div class="moz-cite-prefix">On 10/19/25 19:51, wrote:<br>
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Good evening Dr. Pounds,</div>
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I hope you are well! I'm struggling to get an answer for chapter
6 question 5 part D on osmotic pressure. Would you be able to
explain this part?</div>
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Thanks!</div>
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<p><font face="serif">So in the ideal case the vapor mole fraction
would be the moles of mannitol over the moles of mannitol + the
moles of water. If you multiply this by the vapor pressure of
water you get the amount the vapor pressure of the water was
lowered by the presence of the non-volatile mannitol.</font></p>
<p><font face="serif">Use the observed vapor pressure that was given
to determine the observed vapor pressure lowering, and then the
mole fraction of mannitol. Once you have the mole fraction of
mannitol you can do a little algebra</font></p>
<p><font face="serif">mole fraction of mannitol = moles manitol /
(moles water + moles mannitol)</font></p>
<p><font face="serif">to determine the moles of mannitol in the
solution. You don't have the volume of the mannitol, but in
this case it is negligible compared to the 1000 ml of water.
Then set up the Osmotic pressure equation</font></p>
<p><font face="serif">Pi V = nRT</font></p>
<p><font face="serif">I found it easiest to compute the Osmotic
pressure in atmospheres and then convert to Pascals.</font></p>
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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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