How is CN - a weak base if its the conjugate base of a weak acid?

Question

Guest

Chemistry

15 January, 08:51

How is CN - a weak base if its the conjugate base of a weak acid?

+5

Answers (1)

Know the Answer?

Rodney Horn · Answer 1

The conjugate bases of most weak acids are weak bases.

The only conjugates that are strong bases are those of extremely weak acids, like water (pKa = 14), for which OH - is the conjugate base.

"The conjugate base of a relatively weak weak acid is a relatively strong weak base, and the conjugate base of a relatively strong weak acid is a relatively weak weak base."

NH2 - is the conjugate base of an extremely weak acid, NH3 (pKa = 35). On the otehr hand, CN - is the conjugate base of a moderately weak acid, HCN (pKa = 9.2), so it's a moderately weak base.