Kwas słaby + woda HA + H20 <=> H30+ + A-, K»C0. [HA] = C0
H20 + H20 H30+ + OH-
Równania
[H301 = [A] + [OH]
Ki = [H3O*][A-]/C0 ^A-Kw = [H301[OH ] —» OH' [H30+] 3 (K^C0* KJ* > Kw* ^PH < 7
Gdy Cq —^0 to [H30-]=KJ* PH = 7