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Dissociation constant

In chemistry and biochemistry the dissociation constant, abbreviated Kd, is a measure of the extent to which a dissociation reaction

AB ↔ A + B

proceeds at equilibrium.

It is given quantitatively by the expression

Kd = [A]×[B]×[AB]-1

Where [A], [B], and [AB] indicate the concentrations of A, B, and AB, respectively.

See also hydrogen bond.

The dissociation constant is a specific type of equilibrium constant[?].

The dissociation constant of water (Ke) varies in function of the temperature. The value of pH for neutrality is not the same at different temperatures.

water Ke pKe
0°C 0.1e-14 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 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

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