Enter a pH Value or [H⁺] Concentration into the Hydrogen Ion Concentration Calculator to get [H⁺], pOH, [OH⁻], and Solution Type — or supply a Temperature to calculate [H⁺] in pure water at that condition.
Hydrogen Ion Concentration [H⁺]
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pH Value
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pOH Value
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Hydroxide Ion [OH⁻]
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Solution Type
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A hydrogen ion (H⁺) is also known as a proton. In aqueous solutions, it represents the acidic component and determines the pH of the solution. Higher H⁺ concentrations result in lower pH values (more acidic solutions).
Use the formula [H⁺] = 10^(-pH). For example, if pH = 3, then [H⁺] = 10^(-3) = 0.001 M or 1.0×10⁻³ M. This inverse relationship means lower pH values correspond to higher H⁺ concentrations.
No, enter only one value and leave the other blank. The calculator will compute the missing value automatically. If you enter both, the calculator will use the pH value and recalculate [H⁺].
The temperature option calculates the hydrogen ion concentration in pure water at different temperatures using the temperature-dependent water dissociation constant (Kw). At 25°C, pure water has [H⁺] = 1.0×10⁻⁷ M.
pOH and pH are related by the equation: pH + pOH = 14 (at 25°C). pOH represents the hydroxide ion concentration: pOH = -log[OH⁻]. This relationship helps determine both acidic and basic properties of solutions.
Yes, acids have higher concentrations of hydrogen ions (H⁺) than pure water. Solutions with [H⁺] > 1.0×10⁻⁷ M (pH < 7) are acidic, while those with [H⁺] < 1.0×10⁻⁷ M (pH > 7) are basic.
Scientific notation is recommended for very small or very large concentration values. Hydrogen ion concentrations typically range from 10⁻¹⁴ to 10⁰ M, making scientific notation clearer and more precise than decimal notation.
H⁺ and H₃O⁺ (hydronium ion) are effectively the same in aqueous solutions. H₃O⁺ represents a water molecule (H₂O) combined with a hydrogen ion (H⁺), but both notations refer to the same acidic species in solution.