Weak Acid Calculator — calculate weak acid using standard chemistry formulas. Worked example with units.
pH = −log₁₀[H⁺] (where [H⁺] is in mol/L)
[H⁺] = 10^(−pH)
pOH = −log₁₀[OH⁻] | pH + pOH = 14 (at 25°C)
Henderson-Hasselbalch: pH = pKa + log([A⁻]/[HA]) — for buffer calculations
Weak acid approximation: [H⁺] ≈ √(Ka × C), so pH ≈ ½(pKa − log C)