[CHM 111 Lab] Precision Calculator

[Andrew J. Pounds]

Several of you asked me yesterday about calculating precision and which 
values to use from the data you collected.   Here is the deal.  You all 
should have collected FIVE good sets of data.   I want you to base your 
answer on the THREE MEASUREMENTS that agree the best with each other.  
In other words, your average molarity should be based on the three value 
that produce the smallest PPT.  This could be a very time consuming 
process done by hand -- I mean think about it, all of the possible 
combinations of five pieces of data taken 3 at a time means 10 different 
combinations.  So to help you out I wrote a little web based Java applet 
to help you with your calculations.

http://theochem.mercer.edu/chm111/pptcalc

It does not take into account significant figures!  So use it to get a 
rough idea of what three values to use to get the smallest PPT and then 
evaluate the number accurately using sig figs by hand.

-- 
Andrew J. Pounds, Ph.D.  (pounds at theochem.mercer.edu)
Associate Professor of Chemistry and Computer Science
Mercer University,  Macon, GA 31207   (478) 301-5627