Neutral Hydrogen Concentration

Defines the neutral point where hydrogen equals hydroxide, used to show why neutral pH shifts with temperature as Kw changes.

$$[{\mathrm{H}}^{+}]=\sqrt{K_w}$$

Variables

Symbol	Meaning	Unit
$[{\mathrm{H}}^{+}]$	Hydrogen-ion concentration at neutrality	mol/L
$K_w$	Self-ionization constant of water	mol^2/L^2

Worked example

At 25 C, [H+]^2 = Kw = 10^-14, so [H+] = 10^-7 mol/L and pH = 7.

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Part of The Blueprint of Water