pH Calculator
Calculate pH, pOH, and ion concentrations for acids, bases, and buffers.
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pH
pOH
[H⁺]
[OH⁻]
Nature
About pH Calculations
pH measures the acidity or basicity of a solution on a scale from 0 to 14. A pH of 7 is neutral, below 7 is acidic, and above 7 is basic.
Formulas
- Strong acid: pH = −log[H⁺], where [H⁺] equals the acid concentration
- Strong base: pOH = −log[OH⁻], then pH = 14 − pOH
- Weak acid: Solve Ka = x²/(C − x) for [H⁺], then pH = −log[H⁺]
- Buffer: Henderson-Hasselbalch equation: pH = pKa + log([A⁻]/[HA])