Acids, equilibrium & kinetics · HL
pH, pOH & Kw Calculator (HL)
HL tool. Default Kw = 1.0 × 10⁻¹⁴; change it when temperature-specific data are supplied.
Your values
Start with the example or enter your own values. Use a dot for decimals and e for scientific notation.
Calculated locally. No account or input upload.
Result & working
ExampleThe calculator is loading. The worked example is also shown below.
Step-by-step working
The formula
Kw = [H⁺][OH⁻]
pKw = −log₁₀Kw
pH + pOH = pKw
| Symbol | Meaning |
|---|---|
| Kw | Ionic product of water at the stated temperature. |
When to use this calculator
Using Kw explicitly avoids silently assuming 25 °C when another value is supplied.
Worked example
The page opens with these example values. The result below is pre-generated for reference.
- pKw = −log₁₀Kw = −log₁₀(1e-14) = 14
- pH + pOH = pKw = 14
- Kw = [H⁺][OH⁻] = 1e-14
pH = 3
Common mistakes
- Do not automatically set pH + pOH = 14 unless pKw = 14 for the stated conditions.