How is [H⁺] found from pH?

How do you determine concentration of hydrogen ions when given the pH of a solution? Mamuke, Illinois State University

	Vocabulary
	pH molarity

A simple, working definition of pH is [1]

pH = - log[H⁺]

To obtain the hydrogen ion molarity from the pH, remember that a logarithm of a number is really just the exponent when that number is written as a power of ten:

x = 10^{log x} so the definition of pH solved for hydrogen ion molarity is [H⁺] = 10^-pH For example, the molarity of hydrogen ions in a pH 5 solution is 10^-5 M.

Notes

pH is only approximately equal to minus the log of the hydrogen ion molarity. For details, see "What is pH?"

Author: Fred Senese senese@antoine.frostburg.edu

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Notes

How is [H⁺] found from pH?