Fall 2011 Final Exam Q7A

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Arielle Kunitz 3A
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Joined: Fri Sep 25, 2015 3:00 am

Fall 2011 Final Exam Q7A

Postby Arielle Kunitz 3A » Sat Dec 05, 2015 3:02 pm

The problem asks: which base and its conjugate acid would you choose as optimal for making the buffer and why?

I understand that an optimal buffer has a pH close to the pKa, so does that also mean that the pOH is close to the pKb? That was the way that I solved the problem (pOH rather than pH), since I didn't want to convert the given Kb values to Ka, etc. I got the correct answer except for the explanation.

Basically, is it okay to solve it the way I did? Thank you!

Posts: 22
Joined: Fri Sep 25, 2015 3:00 am

Re: Fall 2011 Final Exam Q7A

Postby LinaLi2E » Sat Dec 05, 2015 3:44 pm

Yes, you should be able to solve the problem by finding out which pOH is closest to pKB. In our course reader, on page 156, it says, "OPTIMUM BUFFERING CAPACITY OIF A WEAK ACID OCCURS WHEN [ACID]=[CONJUGATE CASE] OR FOR WEAK BASE WHEN [BASE]=[CONJUGATE ACID]...pH=pKA (pOH=pKB)"

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