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<p>Class -- I have placed an example of a standardization plot
(yours will have different values) for the Aqueous Equilibrium lab
on the class website...</p>
<p><a class="moz-txt-link-freetext" href="http://theochem.mercer.edu/chm112/aqequil.png">http://theochem.mercer.edu/chm112/aqequil.png</a><br>
</p>
<p>Here is the reaction that we are studying...</p>
<p>Fe<sup>3+</sup> (aq) + SCN<sup>-</sup> (aq) -> FeSCN<sup>2+</sup>
(aq)</p>
<p>This is a NET IONIC reaction. The iron (III) and thiocyanate
ions are delivered to the solution by the strong electrolytes
Fe(NO<sub>3</sub>)<sub>3</sub> and KSCN. You will therefore use
the volumes and concentrations of those solutions, as well as the
volume of the nitric acid, to compute the initial concentrations
of the iron (III) and thiocyanate ions.</p>
<p>For the first part of the reaction where you are computing the
standards for your plot, the iron (III) concentation is MUCH
larger than that of the thiocyanate, so you will be, according to
LeChatelier's principle, be driving the equilibrium all the way to
the right. That means that initial concentration (after computing
you dilutions) of the FeSCN<sup>2+</sup> ion is the same as the
SCN<sup>-</sup> ion.</p>
<p>This will emphatically not be the case for the second part of the
lab. I will provide more information on that later -- but you
should have enough now to go ahead and build your calibration
plots before class tomorrow.</p>
<p><br>
</p>
<div class="moz-signature">-- <br>
<b><em>Andrew J. Pounds, Ph.D.</em></b><br>
<em>Professor of Chemistry and Computer Science</em><br>
<em>Director of the Computational Science Program</em><br>
<em>Mercer University</em><br>
<em>1501 Mercer University Drive, Macon, GA 31207 </em><br>
<em>(478) 301-5627</em><br>
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