6.2.2

Ionic Product of Water

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The Ionic Product of Water

Water is very slightly dissociated into its ions.

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Dissociation of water

  • Water very slightly dissociates into it's ions according to the following equation:
    • 2H2O(l) ⇋ H3O+(aq) + OH-(aq)
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Equilibrium constant

  • The equilibrium constant for the dissociation of water is:
    • Kc = [H3O+][OH][H2O]\frac{[H_3O^+][OH^-]}{[H_2O]}
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Ionic product of water

  • The equilibrium constant can be simplified because the concentration of water is pretty much constant.
    • Water only dissociates slightly, so the concentration doesn’t really change.
    • We write a new equation: Kw = [H3O+(aq)][OH-(aq)]
Illustrative background for Temperature dependence of K<sub>w</sub>Illustrative background for Temperature dependence of K<sub>w</sub> ?? "content

Temperature dependence of Kw

  • Kw is just an equilibrium constant.
    • Because of this, it behaves the same as any other equilibrium constant, Kc.
  • Importantly, this means it has a temperature dependence. The hotter the water is, the more dissociated it is and the larger its Kw value.

Jump to other topics

1Structure - Models of the Particulate of Matter

2Structure - Models of Bonding & Structure

3Structure - Classification of Matter

3.1The Periodic Table: Classification of Elements

3.2Periodic Trends

3.3Group 1 Alkali Metals

3.4Halogens

3.5Noble gases, group 18

3.6Functional Groups: Classification of Organic

3.7Functional Group Chemistry

3.8Alkanes

3.9Alcohols

3.10Halogenoalkanes

4Reactivity - What Drives Chemical Reaction?

5Reactivity - How Much, How Fast & How Far?

6Reactivity - The Mechanisms of Chemical Change

7Measurement, Data Processing & Analysis

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