THE pK_a BOX

The pK_a of an acid is a very useful number, as you will see in the math below. The pKa is the negative log of the k_a, the pK_b is the negative log of the k_b, and the pK_a plus the pK_b equal fourteen. The k_a box is the same as the pH box, but substitute k_a for [H⁺], pK_a for pH, k_b for [OH^-], and pK_b for pOH.