\({K_h} = \frac{{{K_w}}}{{{K_a} \times {K_b}}}\)
\(log K_h - log K_w - log K_a - log K_b\)
\(- log Kh = -log Kw + log Ka + log Kb\)
\(pK_h = pK_w - pK_a - pK_b\)
\(pK_h = 14 + logK_a - pK_b \)