Estimate pH from hydronium concentration in a dilute aqueous solution.
Difficulty
Beginner
Read time
3 min
Prerequisites
Basic algebra and molar quantities
Source
OpenStax, Chemistry 2e, §14.2Adapted from Teng-Jui Lin’s CHEM 155 equation sheet. The linked textbook reference was used to check the equation and its physical context. Pending editorial review.
Adapted from Teng-Jui Lin, Equation Sheets, under CC BY 4.0.
FormuLab adapted notation and chemical symbols, added variable meanings, units, applicability conditions, and an original worked example. Made the standard-concentration normalization and dilute-solution approximation explicit.
pH is defined using hydronium activity. In a sufficiently dilute solution, activity is approximated by concentration divided by the standard concentration, giving the familiar base-10 logarithm calculation.
| Symbol | Meaning | Units |
|---|---|---|
| pH of the solution | ||
| Hydronium concentration | ||
| Standard concentration, 1 mol/L |
Estimate pH from a dilute-solution hydronium concentration.
Recognize that a tenfold concentration change changes pH by one.
Estimate the pH of a dilute solution with hydronium concentration 5.00 × 10⁻⁴ mol/L.
Adapted from Teng-Jui Lin’s CHEM 155 equation sheet. The linked textbook reference was used to check the equation and its physical context. Pending editorial review.
Adapted from Teng-Jui Lin, Equation Sheets, under CC BY 4.0.
FormuLab adapted notation and chemical symbols, added variable meanings, units, applicability conditions, and an original worked example. Made the standard-concentration normalization and dilute-solution approximation explicit.
Assumptions
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