ACID/BASE “TOOLBOX”

Shown here are the basic tools one needs to be able to calculate hydronium ion, hydroxide ion, pH, pOH, K_a, and K_b. when dealing with acid/base problems. I call it my “toolbox” and hope you find it useful!

Fundamental equations:

[H₃O⁺][OH¯] = K_w = 1.0 x 10^-14 pX = -logX K_aK_b = K_w

All the ways you can find [H₃O⁺] and [OH¯]:

All the ways you can find pH and pOH:

pH + pOH = 14 pH = 14 – pOH pOH = 14 – pH

pH = -log[[H₃O⁺] pOH = -log[OH¯]

K_aK_b = K_w is used in hydrolysis problems. Use it to calculate the K_b of the conjugate base of a weak acid, or conversely, the K_a of the conjugate acid of a weak base:

In general, pX is a power function, and it means you take the negative logarithm of the variable or number, hence, pX = -logX.