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This is a reminder to look at my help files for exp 17. I have both
pre-lab <br>
and post-lab hints and help.<br>
<br>
There is both a pre-lab and post-lab on Carmen for exp 17.<br>
<br>
Please look at the pre-lab help before going to lab. You are
making four<br>
solutions by mixing Cr^3+ and EDTA- resulting in different conc. of
Cr^3+<br>
in each solution. You should have a table like Table 17.1 on page
44 of the<br>
manual. You may not necessarily have the exact values for the
volumes of<br>
the Cr(NO3)3 since you are using a buret (you shouldn't even try to
get<br>
those exact volumes since it can take longer than necessary). You
will<br>
record the actual volumes of the Cr(NO3)2 solution you measure. <br>
<br>
A <b>10</b>-mL pipet is being used for the EDTA. You use it to
measure out a<br>
total of 20-mL of EDTA in each test tube.<br>
<br>
Each partner should have 4 LARGE test tubes (the ones marked as
75-mL<br>
with the large openings), marked 1-4. One partner measures out the
Cr^3+<br>
and the other measures out the EDTA.<br>
<br>
For the data collection of the absorbances of the four solutions,
you want a<br>
<b>SINGLE</b> table for the time and absorbance data for the four
solutions on a<br>
single page. You should have a table with 8 columns, in groups of
two for<br>
each solution, marked something like <br>
<br>
<table height="97" border="1" cellpadding="2" cellspacing="2"
width="557">
<tbody>
<tr>
<td valign="top">soln 1</td>
<td valign="top"><br>
</td>
<td valign="top">soln 2<br>
</td>
<td valign="top"><br>
</td>
<td valign="top">soln 3</td>
<td valign="top"><br>
</td>
<td valign="top">soln 4</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">time (min)<br>
</td>
<td valign="top">Abs<br>
</td>
<td valign="top">time (min)</td>
<td valign="top">Abs</td>
<td valign="top">time (min)</td>
<td valign="top">Abs<br>
</td>
<td valign="top">time (min)</td>
<td valign="top">Abs</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
This table should be big enough to record at least 15 lines of time
and Abs data.<br>
<br>
You will also need to have space for recording the initial conc. of
the Cr^3+ in<br>
each soln., the conc. of the CrEDTA- product and the absorbance
values for the<br>
product in the boiled solutions.<br>
<br>
<br>
<a
href="http://chemistry.osu.edu/%7Erzellmer/chem1220/lab/lab_1220.htm"><b>Laboratory</b></a>
(see stuff dealing with exp 17)<br>
<br>
<a
href="http://chemistry.osu.edu/%7Erzellmer/chem1220/faq/exp17_help.txt"><b>Pre
and Post-lab Help for Exp 17 - (Answers to Students' Questions)</b></a><br>
<br>
<a
href="http://chemistry.osu.edu/%7Erzellmer/chem1220/lab/exp17_tips.pdf"><b>Handout
for Exp. 17 - Report Tips (Data Analysis)</b></a><br>
<br>
I HIGHLY suggest you use Excel (or something similar) to do the data
tables, calculations and graphs.<br>
<br>
<a
href="http://chemistry.osu.edu/%7Erzellmer/chem1220/lab/exp17/exp17.htm"><b>Exp
17 - Using MS Excel</b></a><br>
<br>
There are a lot of calculations (a minimum of 245). If you make a
mistake you often don't realize<br>
it until you do graph 2 (zero-order plot). Then you have to go back
and redo almost all the calculations.<br>
Using Excel makes the whole process easier, even if you don't make a
mistake.<br>
<br>
More to follow...<br>
<br>
Dr. Zellmer
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