So when we say that the pH is the negative log of the hydrogen ion concentration...

因为10的2次方。

Just as we can calculate the pH of a substance from it's hydrogen ion concentration, we can calculate the pOH.

就是一种在不同pH值环境中会显现不同颜色的化学物质。

(4). Regulation of plasma hydrogen ion concentration (pH).

(4)。调节氢离子浓度(pH)。