Problem 12.45 (6th edition)

The Conjugate Seesaw

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Problem 12.45 (6th edition)

Postby pamcoronel1H » Wed Jan 23, 2019 11:24 pm

I am confused about the pattern of strength described in the solution. In my lecture notes I have it that the stronger the acid, the weaker it conjugate base, so that would be that a higher pKa would mean a lower kb and therefore a weaker conjugate base, right?

The solutions manual says that the stronger the pKa the stronger the conjugate base, so now I am confused on which pattern is right. Could someone explain the relationship between pKa and the strength of its conjugate base?


(By the way, for my answer I put d>a>b>c, which was the complete opposite of the answer)

Eshwar Venkat 1F
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Joined: Fri Sep 28, 2018 12:22 am

Re: Problem 12.45 (6th edition)

Postby Eshwar Venkat 1F » Wed Jan 23, 2019 11:45 pm

The trend is that the higher the pKa value, the weaker the acid, and the stronger the base, the weaker its conjugate acid will be. As a result, the base strengths for this problem correspond to the increasing pKa values for the conjugate acids.

Vicky Lu 1L
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Joined: Fri Sep 28, 2018 12:18 am

Re: Problem 12.45 (6th edition)

Postby Vicky Lu 1L » Wed Jan 23, 2019 11:50 pm

The trend is that the a smaller pKa/larger the Ka, the stronger the acid and the larger the pKb/smaller the Kb, the stronger the acid. Likewise, the smaller the pKb/larger the Kb, the stronger the base and the larger the pKA/smaller Ka, the stronger the base.

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