How to determine whether a molecule is a stronger/weaker base or conjugate acid than the other?

Question

I've always thought of acids and bases only in terms of acid and conjugate base, with electronegative atoms/resonance being able to stabilize the conjugate base, thus making it a weaker conjugate base and a correspondingly stronger acid. Does this thinking apply to bases/conjugate acids too?

Answer 1

You are absolutely correct. There is even a table is freshman chemistry textbook showing strong acids producing weak conjugate bases and strong bases producing weak conjugate acids. This table in my textbook is called "Relative Strengths of Conjugate Acid-Base Pairs".

For example, as you are saying, HCl is strong acid. It has a weak conjugate base, ^-Cl. In contrast, Hydroxide is a strong base. it has a weak conjugate acid in water.