<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">On 07/14/14 21:35, wrote:<br>
</div>
<blockquote
cite="mid:C40B2F181831EF44A88CD73525827803130774D82E@MERCERMAIL.MercerU.local"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<style type="text/css" style="display:none"><!-- p { margin-top: 0px; margin-bottom: 0px; }--></style>
<div id="OWAFontStyleDivID"
style="font-size:12pt;color:#000000;background-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;">
<div style="color: rgb(33, 33, 33);">Good evening, </div>
<div style="color: rgb(33, 33, 33);">I am working on Lab 8.</div>
<div style="color: rgb(33, 33, 33);">under the Equillibrium
section for our 5 test tubes there is a section for values of
FeSCN2+, Fe3+, and SCN-. How do we compute the values for
those answers?</div>
<div style="color: rgb(33, 33, 33);">Thank you for your time,</div>
<div style="color: rgb(33, 33, 33);"><br>
</div>
<div style="color: rgb(33, 33, 33);"> </div>
</div>
</blockquote>
<font face="serif">In the first part of the lab (when you built the
Beer's law plot) all of the SCN- was converted to FeSCN2+ -- so
the concentration of FeSCN2+ was equal to the initial
concentration of SCN-. This is not the case in the equilibrium
section and we need some way to determine the equilibrium
concentrations.<br>
<br>
This is where your calibration curve comes in. You measured the
absorbance for each of the tubes in the equlibrium section of the
lab. In each case you were measuring the absorbance of FeSCN2+
(just like you did in the first part). In this second part,
however, you don't initially know the concentrations of the
FeSCN2+ at equilibrium -- but you can use the absorbance AND your
calibration plot to determine it.<br>
<br>
For each of your solutions in the equilibrium section, determine
the concentration of FeSCN2+ at equilibrium by finding that
corresponding concentration for the measured absorbance on your
plot. Write that down.<br>
<br>
Remember, for each solution you are going to have to build an ice
table. As such, for each solution you have an initial Fe3+, SCN-
and FeSCN2+ concentration (the last one will be zero each time).
You also - based on your measured absorbance and interpolated
concentration, know the EQUILIBRIUM CONCENTRATION OF FeSCN2+.
Fill this out on your ICE table. This will be the value of "x"
in your ICE table. Use this to determine the equilibrium
concentrations of Fe3+ and SCN-.<br>
<br>
<br>
</font><br>
<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
Mercer University, Macon, GA 31207 (478) 301-5627
<a class="moz-txt-link-freetext" href="http://faculty.mercer.edu/pounds_aj">http://faculty.mercer.edu/pounds_aj</a>
</pre>
</body>
</html>