Water Autoionization

概要

Water undergoes autoionization where one molecule acts as an acid (donates H⁺) and another acts as a base (accepts H⁺). The equilibrium constant Kw = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25 C, defining pH 7 as neutral. This endothermic reaction shifts right at higher temperatures, decreasing neutral pH.

参加者

日常の例

The pH scale itself is defined by water autoionization, which is why pH 7 is neutral at 25 C and why neutral pH changes at different temperatures.

産業上の重要性

Kwの理解はすべての水溶液化学、pH測定、水質分析、緩衝液の設計に不可欠である。