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Q98

Q98

Postby SeoM » Wed Apr 01, 2020 10:42 pm

"The pKa of acteic acid is 5. What is the pH at which the concentration of acetic acid will be 10^3 that of it's conjugate base?" I am confused as to where the 10^-3 came from in the solution.
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Re: Q98

Postby goldstanda3269 » Thu Apr 02, 2020 3:57 pm

SeoM wrote:"The pKa of acteic acid is 5. What is the pH at which the concentration of acetic acid will be 10^3 that of it's conjugate base?" I am confused as to where the 10^-3 came from in the solution.


Given the information in the passage, let the protonated form AH = acid, and the deprotonated form A- = base, and keep in mind that we have 10^3 times more acid than base (information given in the question), therefore:

[A-]/[AH] = [A-] / (10^3 x [A-]) = 1 / 10^3 = 10^-3

Please note, the manipulations done in this question are helpful for:

Purple booklet questions 104-107

Pink booklet questions 10 and 110.
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