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Weak Acids

Posted: Sun Nov 11, 2012 7:57 pm
by Potions09
In my textbook, it says some weak bases are the anions of weak acids, for example F- in HF. But I thought that the conjugate base of weak acids are strong bases?

Strength is relative.

Posted: Mon Nov 12, 2012 1:53 am
by GrahamKemp
Yes, in general the stronger an acid the weaker the conjugate base, and vice versa.

However, strength is relative. While there are acids stronger than hydroflouric, many are weaker.

At pKa=3.17, HF is a medium strength acid; and its conjugate F- is a very weak base at pKb = 10.83.

pKa + pKb = 14

http://chemed.chem.wisc.edu/chempaths/G ... s-958.html