[CHM 330] Worksheet Question

[Andrew J. Pounds]

On 9/26/22 13:32,  wrote:
> Dear Dr. Bounds,
>
> For the question you just posted in the examples, how would you 
> determine the bounds for the solver calculations? How did you know the 
> upper bounds was equal to 0.6? Do you just make a guess and see if it 
> makes the original equation equal to 0? I may have missed this in my 
> notes.
> Please get back to me as soon as you are able.
>
Dr. Bounds -- that's funny...  Assuming it was a Freudian slip based on 
the question...

So in solving these we have to remember that our 
CONCENTRATIONS/PRESSURES can never be negative.  In fact, we have 
carefully constructed our ice table so we can enforce this constraint.  
With that said, look at the two term in the law of mass action that 
could become negative.

(2−3x)3(3−5x)5(2-3x)^3 (3-5x)^5

The term on the left would be negative if x exceeded 2/3 (which is 
0.6666).   The term on the right would be negative if x exceeded 3/5 
(which is 0.6).  I select whichever one of these is the SMALLEST for my 
upper bound.

That should make sense, because if I plugged 0.6666 into the term on the 
right it would be negative.

Does that help?

-- 
*/Andrew J. Pounds, Ph.D./*
/Professor of Chemistry and Computer Science/
/Director of the Computational Science Program/
/Mercer University, Macon, GA 31207 (478) 301-5627/
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