Work out hydrogen ion concentration instantly with clear inputs, formula shown and shareable results.
pH is defined as the negative base-ten logarithm of the hydrogen ion concentration, so inverting it is a matter of raising ten to the negative pH. A pH of 7 gives exactly 1e-7 mol/L, and the hydroxide concentration follows from Kw = [H+][OH-], which at 25 C is 1.0e-14.
Hydrogen ion concentration
[H+] = 10^-pH
Hydroxide from Kw
[OH-] = Kw / [H+]
Exactly 1x10^-7 mol/L, and [OH-] is the same, which is what makes pH 7 neutral at 25 C.
Because it is temperature dependent. At 50 C Kw is about 5.5e-14, so neutral pH is nearer 6.6 than 7.