The conjugate base of a weak acid is a weak base according to Daniel C.Harris Quantitative Chemical Analysis, Is this correct?
I thought The conjugate base of a weak acid is a strong base?
From Daniel C.Harris Quantitative Chemical Analysis,
"The conjugate base of a weak acid is a weak base. The conjugate acid of a weak base is a weak acid. Consider a weak acid, HA, with Ka=10^-4. The conjugate base, A-, has Kb= Kw/Ka=10^-10. That is, if HA is a weak acid, A- is a weak base. If Ka were 10^-5, then Kb would be 10^-9. As HA becomes a weaker acid, A- becomes a stronger base (but never a strong base). Conversely, the greater the acid strength of HA, the less the base strength of A-. However, if either A- or HA is weak, so is its conjugate. If HA is strong (such as HCl), its conjugate base (Cl-) is so weak that it is not a base at all in water."