How to use (3 steps)
- Choose a mode: single solution or strong acid–strong base mixture.
- Enter concentrations (and volumes for mixtures). For weak species, choose Ka/pKa or Kb/pKb.
- Compute to see pH, pOH, key concentrations, and the calculation steps. Copy the URL to share.
Default sample values are prefilled so you can compute pH right away. All calculations run in your browser only.
Results
Solution details
| pH | — |
|---|---|
| pOH | — |
| [H⁺] (mol/L) | — |
| [OH⁻] (mol/L) | — |
| α (dissociation) | — |
Mixture details
| Initial moles acid n_a | — |
|---|---|
| Initial moles base n_b | — |
| [H⁺] (mol/L) | — |
| [OH⁻] (mol/L) | — |
| pH | — |
| pOH | — |
| Excess side | — |
How it's calculated
- Steps will appear here after calculation.
Use this page when you need one acid-base check in one place
This calculator works best for quick classroom verification and lab-prep checks with monoprotic acids or monobasic bases. Keep the mode fixed, confirm the concentration inputs, then compare the reported pH, pOH, and concentration outputs with the calculation steps below.
Single solution workflow
- Choose the species type first so the page knows whether to use direct strong-acid/base logic or the weak-acid/base equilibrium path.
- Enter the concentration, then add Ka/pKa or Kb/pKb only when you are working with a weak species.
- Compute once, read the summary values, and use the step log to verify how the page reached the final pH.
Mixture workflow
Use mixture mode when you are combining a strong acid and a strong base. Enter both concentrations and both volumes, then check which side is in excess before you interpret the final pH. This page keeps all volumes in liters and concentrations in mol/L to reduce unit drift.
What to check before trusting the result
- Make sure the solution type matches the chemistry you actually have.
- Check whether your Ka/pKa or Kb/pKb value is for the same temperature and species.
- Remember that this tool assumes ideal behavior near 25 °C and does not model activity coefficients.
Best next pages
FAQ
Can this handle weak acids and bases?
Yes. Enter the concentration and Ka (or pKa) for a weak acid, or Kb (or pKb) for a weak base. The calculator solves the quadratic exactly instead of using small-x approximations.
What assumptions does this calculator make?
It assumes monoprotic acids and monobasic bases at about 25 °C, ignores activity coefficients, and uses Kw = 1.0×10⁻¹⁴. Extremely dilute solutions may deviate from these ideal assumptions.
What can I compute in the strong acid–strong base mixing mode?
Enter the concentration and volume of the acid and base. The tool computes initial moles, determines which side is in excess, and returns [H+], [OH-], pH, and pOH. At equivalence it reports pH ≈ 7.
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