Home Up Self-Ionization of Water Definition of pH Hydronium-Hydroxide Balance Kw Calculating H-OH Ion Concentrations Calculating pH and pOH



The relationship between the concentration of H3O+ and the concentration of OH- shows a very consistent pattern.

That pattern can be expressed mathematically by saying that the product of the concentration of H3O+ times the concentration of OH- remains a constant value of 1.0 x 10-14.

That value has both a name and a symbol. It is variously called the ion product constant for water,   the ionization constant of water,or simply the water constant. The symbol is Kw. You should write down this relationship in your workbook.

[H3O+] x [OH-] = 1.0 x 10-14
[H3O+] x [OH-] = Kw


This equation for the ionization constant of water can be used in anumber of calculations, as you will see next.


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E-mail instructor: Eden Francis

Clackamas Community College
1998, 2002 Clackamas Community College, Hal Bender