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relationship between Ka, Kb, and its ability to donate

Posted: Wed Jan 16, 2019 4:13 pm
by Hai-Lin Yeh 1J
Is this correct:
The smaller the value of Ka, the weaker the ability of the acid to donate a proton, but the greater the value of pKa. This also means the acid is very weak. Similarly, the smaller the value of Kb, the weaker the ability of the base to accept a proton, but the greater value of pKb. This means the base is also very weak?

Re: relationship between Ka, Kb, and its ability to donate

Posted: Wed Jan 16, 2019 4:23 pm
by Rachel-Weisz3C
That sounds right! Also, as Ka increases, Kb decreases and vice versa, since Ka x Kb = Kw.

Re: relationship between Ka, Kb, and its ability to donate

Posted: Thu Jan 17, 2019 4:08 pm
by Riya Shah 4H
So if you are given a pKa value of a conjugate acid which is large, does that mean the base is strong?

Re: relationship between Ka, Kb, and its ability to donate

Posted: Thu Jan 17, 2019 4:12 pm
by Max Hayama 4K
I believe this is correct! If the conjugate acid has a high pKa, the Ka value is small, meaning the ability to donate a proton is not strong. Therefore the ability for the conjugate acid to form the base is also small, meaning the base is strong.