Exp 17 help - both pre and post lab, using Excel

[robert zellmer]

This is a reminder to look at my help files for exp 17.  I have both 
pre-lab
and post-lab hints and help.

There is both a pre-lab and post-lab on Carmen for exp 17.

Please look at the pre-lab help before going  to lab.  You are making four
solutions by mixing Cr^3+ and EDTA- resulting in different conc. of Cr^3+
in each solution.  You should have a table like Table 17.1 on page 44 of the
manual.  You may not necessarily have the exact values for the volumes of
the Cr(NO3)3 since you are using a buret (you shouldn't even try to get
those exact volumes since it can take longer than necessary).  You will
record the actual volumes of the Cr(NO3)2 solution you measure.

A *10*-mL pipet is being used for the EDTA.  You use it to measure out a
total of 20-mL of EDTA in each test tube.

Each partner should have 4 LARGE test tubes (the ones marked as 75-mL
with the large openings), marked 1-4.  One partner measures out the Cr^3+
and the other measures out the EDTA.

For the data collection of the absorbances of the four solutions, you want a
*SINGLE* table for the time and absorbance data for the four solutions on a
single page.  You should have a table with 8 columns, in groups of two for
each solution, marked something like

soln 1 	
	soln 2
	
	soln 3 	
	soln 4 	
time (min)
	Abs
	time (min) 	Abs 	time (min) 	Abs
	time (min) 	Abs

	
	
	
	
	
	
	


This table should be big enough to record at least 15 lines of time and 
Abs data.

You will also need to have space for recording the initial conc. of the 
Cr^3+ in
each soln., the conc. of the CrEDTA- product and the absorbance values 
for the
product in the boiled solutions.


*Laboratory* 
<http://chemistry.osu.edu/%7Erzellmer/chem1220/lab/lab_1220.htm> (see 
stuff dealing with exp 17)

*Pre and Post-lab Help for Exp 17 - (Answers to Students' Questions)* 
<http://chemistry.osu.edu/%7Erzellmer/chem1220/faq/exp17_help.txt>

*Handout for Exp. 17 - Report Tips (Data Analysis)* 
<http://chemistry.osu.edu/%7Erzellmer/chem1220/lab/exp17_tips.pdf>

I HIGHLY suggest you use Excel (or something similar) to do the data 
tables, calculations and graphs.

*Exp 17 - Using MS Excel* 
<http://chemistry.osu.edu/%7Erzellmer/chem1220/lab/exp17/exp17.htm>

There are a lot of calculations (a minimum of 245).  If you make a 
mistake you often don't realize
it until you do graph 2 (zero-order plot).  Then you have to go back and 
redo almost all the calculations.
Using Excel makes the whole process easier, even if you don't make a 
mistake.

More to follow...

Dr. Zellmer
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