It is sometimes stated that "the conjugate of a weak acid is a strong base". Such a statement is incorrect. For example, acetic acid is a weak acid which has a  = 1.75 x 10. Its conjugate base is the acetate ion with K = 10/K = 5.7 x 10 (from the relationship K × K = 10), which certainly does not correspond to a strong base. The conjugate of a weak acid is often a weak base and vice versa.