Poh Calculator
What pOH corresponds to this hydroxide ion activity? Enter the stated values to calculate this model.
Reference calculation or estimate for example inputs; assumptions and limitations apply.
Calculations run in your browser.
Assumptions / Standards / Limitations
Input is positive dimensionless hydroxide-ion activity. Concentration approximation is limited by activity effects. pH+pOH depends on temperature through pKw; 14 is not a universal constant.
Model reference: OpenStax Chemistry 2e; supplementary IUPAC definition where listed. Last verified: 2026-10-08. This is a scientific reference model; no regulatory code or installation standard is used.
Example inputs illustrate the calculation. They are not recommended preparation, installation or operating settings.
What to enter
| Input | Meaning and units |
|---|---|
| Hydroxide ion activity (1) | Enter hydroxide ion activity in 1; use the same basis as the other measurements. |
Understanding your result
The result is a scientific reference calculation under the model assumptions on this page. It does not assess hazards, chemical compatibility, purity, solubility, equipment limits or clinical meaning.
Common mistakes
- Using solvent volume in place of final solution volume, or mass concentration in place of molar concentration.
- Ignoring units, reaction coefficients, activity assumptions or the stated temperature/model limits.
Check your calculation
- Check the units and balance/coefficients against the worked example. For real laboratory work, verify SDS information and the applicable procedure independently.
Calculation checks, sources and review limits
What pOH corresponds to this hydroxide ion activity?
What pOH corresponds to this hydroxide ion activity? Enter the stated values to calculate this model.
Common uses
- What pOH corresponds to this hydroxide ion activity
How it works
Take the negative base-10 logarithm of hydroxide-ion activity. Temperature and nonideal activity effects matter when relating pOH to other chemical quantities.
Worked example
Enter Hydroxide ion activity: 0.00001 1. Results: pOH: 5 1.