Dissociation Constant - Dissociation Constant of Water

Dissociation Constant of Water

As a frequently used special case, the dissociation constant of water is often expressed as Kw:

The concentration of water is not included in the definition of Kw, for reasons described in the article equilibrium constant.

The value of Kw varies with temperature, as shown in the table below. This variation must be taken into account when making precise measurements of quantities such as pH.

Water temperature Kw / 10−14 pKw
0°C 0.1 14.92
10°C 0.3 14.52
18°C 0.7 14.16
25°C 1.2 13.92
30°C 1.8 13.75
50°C 8.0 13.10
60°C 12.6 12.90
70°C 21.2 12.67
80°C 35 12.46
90°C 53 12.28
100°C 73 12.14

Read more about this topic:  Dissociation Constant

Famous quotes containing the words constant and/or water:

    “A tart temper never mellows with age, and a sharp tongue is the only edged tool that grows keener with constant use.”
    —Washington Irving (1783–1859)

    “But the beggar gazes on calamity
    And thereafter he belongs to it, to bread
    Hard found, and water tasting of misery.”
    —Wallace Stevens (1879–1955)