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<div class="moz-cite-prefix">On 10/17/20 2:24 PM, wrote:<br>
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cite="mid:7f03f90a47b14319979dee25f7a404e8@BN3PR01MB1969.prod.exchangelabs.com">
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Dear Dr. Pounds,</div>
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To find the molecular formula, we are supposed to divide the
molar mass of the substance by the molar mass of the empirical
formula. However, on the report it asks us to put the molar mass
based on the molecular formula. So, I am a little confused. Do
we use the first molar mass to find the molecular formula and
then find the molar mass again to compare the two or do we use
something else to find the molecular formula? I tried asking
some of the people in the class, but they were also a little
confused. </div>
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Sincerely, </div>
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<p><font face="serif">Use the method from page 115-116 to find the
empirical formula. Your empirical formula will have a mass -
calculate it. Then based on the average molar mass that you
determined experimentally and the empirical mass that you
determined from the elemental analysis, figure out how many
"empirical masses" you have.</font></p>
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<p><font face="serif">Lets imagine that from my elemental analysis I
determined that my empirical formula was <img
alt="$\mathrm{C_3H_6O}$" style="vertical-align: -2px;"
src="cid:part1.F4BFC7C4.26B408A9@mercer.edu">, which has a
mass of 58 g/mol. I my determined molar mass from the
experiment was close to 60, then I would conclude that </font><font
face="serif"><img alt="$\mathrm{C_3H_6O}$"
style="vertical-align: -2px;"
src="cid:part1.F4BFC7C4.26B408A9@mercer.edu"> was the
molecular formula. If my determined molar mass from the
experiment was closer to 120, then I would conclude that the
molecular formula was </font><font face="serif"><img
alt="$\mathrm{C_6H_{12}O_2}$" style="vertical-align: -2px;"
src="cid:part3.467DB6CB.3C80965A@mercer.edu">. If the
determined molar mass from the experiment was closer to 180,
then I would conclude that the molecular formula was </font><font
face="serif"><img alt="$\mathrm{C_9H_{18}O_3}$"
style="vertical-align: -2px;"
src="cid:part4.B94F8CCB.845C4054@mercer.edu">. </font></p>
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<pre class="moz-signature" cols="72">--
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
Director of the Computational Science Program
Mercer University, Macon, GA 31207 (478) 301-5627
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