Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: _Alexis_ on September 03, 2022, 07:09:32 PM
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Hello, this is for Biochemistry, but the math is basically high school Chemistry. Unfortunately, I've forgotten a lot of the logic when it comes to ICE problems. I'm trying to find the PH of a buffer after some strong base has been added to acetic acid. What do I do if more mols of the strong base are more than acetic acid? I wrote the formula (PH= pka + log(B/A)) afterward, but a negative value cannot be logged.
Here is what the ICE chart looks like:
CH3COOH + KOH <-> CH3COO- + H2O
I 0.005 0.00525 0 -
C -0.00525 -0.00525 +0.00525 -
E -0.00025 0 0.00525
As you can see, I have a negative value for CH3COOH. That negative value cannot be put into log, so what do I do?
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Have you heard of the concept of the limiting reagent? What happens when all the acetic acid has reacted?
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Yes. Does this mean I solve and add together the PH together of (0.005 mols) CH3COO- and KOH (0.00025mols)
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No. [OH-] will give you [H+] directly.
PS You do not have a buffer here!