[CHM 112] Burdge

[Andrew J. Pounds]

 From step 1 the hydronium ion concentration was 0.0397.  In the second 
and third equilibrations I would  calculate x values that had to be 
ADDED  to 0.0397 to get the total hydronium ion concentration.  In step 
two that value was 0.0000000625.  In the third step it would have been 
even smaller based on the relative size of Ka3.  Since both of these are 
insignificant compared to 0.0397, I just based the pH off of the 0.0397.

You cannot always assume that the other steps are insignificant but you 
can assume that if the second step is insignificant then the third step 
is insignificant too.


On 07/21/13 21:01, Mary Caroline Logan wrote:
> For question number 16.84: after you calculate the concentrations of 
> the second reaction, why did you stop? Is it a general rule that if x 
> is insignificant in comparison to the x of the previous reaction, then 
> you stop? I'm confused. I continued on and calculated the third x the 
> same way I had before with the Ka3, and I ended up with a ph of 7.2, 
> which seemed way too high.
>
> Caroline Logan
>

-- 
Andrew J. Pounds, Ph.D.  (pounds_aj at mercer.edu)
Professor of Chemistry and Computer Science
Mercer University,  Macon, GA 31207   (478) 301-5627
http://faculty.mercer.edu/pounds_aj

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://theochem.mercer.edu/pipermail/chm112/attachments/20130722/e21efbb4/attachment.html>