Science & engineering
pH, pOH & concentration
Relate pH, pOH and idealised hydronium/hydroxide concentrations using a stated pKw.
A clear answer. Here’s how.
Uses pH≈−log₁₀[H₃O⁺], pOH=pKw−pH, [H₃O⁺]≈10⁻pH and [OH⁻]≈10⁻pOH. Concentrations are approximations to activities. The common pKw=14 applies approximately at 25 °C for dilute aqueous conditions; enter the appropriate value yourself. Does not restrict all solutions to pH 0–14 or infer temperature, chemical composition or clinical meaning.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Known input
- pH
- pH
- 7
- pKw for your temperature and conditions
- 14
Example result
- pH
- 7
- pOH
- 7
- Approximate hydronium concentration
- 1E-7 mol/L
- Approximate hydroxide concentration
- 1E-7 mol/L
- Supplied pKw
- 14