It is very pertinent to make some general observations about relative acidity and basicity of the members of a conjugate pair. Recall that the members of an acid-base conjugate pair differ by H
+, for example: HF/F
–, H
2O/OH
–.
In general:
- If one member of the conjugate pair is strong, the other reacts with water to less than 1% and therefore doesn't change the pH of water.
- Weak acids have weak conjugate bases.
nonacidic
H2O | weak acids
HF | strong acids
HCl |
strong bases
OH– | weak bases
F– | non basic
Cl– |
s