What does [H+] represent?

The molar concentration of hydrogen ions (or more precisely, hydronium ions H3O+) in solution.

How does [H+] change with each pH unit?

Each pH unit represents a 10-fold change. pH 3 has 10× more H+ than pH 4.

What is [H+] at neutral pH?

At pH 7: [H+] = 10^-7 = 0.0000001 M.

Free Hydrogen Ion Calculator

Calculate the hydrogen ion concentration from pH.

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[H+] Concentration

0.0010000000 M

[H+] Concentration vs pH

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How to Calculate [H+] from pH

Formula

[H+] = 10^(-pH)

The inverse of the pH equation.

Example Calculation

Find [H+] for pH = 3.

01[H+] = 10^(-3)
02[H+] = 0.001 M

Frequently Asked Questions

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