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Weak Acid Percent Ionization and Ka Calculator

α = [H⁺]/C₀ — fraction of weak acid that ionizes.

Calculates H⁺ concentration and percent ionization α for a weak acid HA ⇌ H⁺ + A⁻ using Ka. Solves the quadratic for [H⁺] = (−Ka + √(Ka²+4Ka·C₀))/2.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

mol/L

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

[H⁺] = (−Ka + √(Ka²+4Ka·C₀))/2; α = [H⁺]/C₀ × 100

In depth

Calculates H⁺ concentration and percent ionization α for a weak acid HA ⇌ H⁺ + A⁻ using Ka. Solves the quadratic for [H⁺] = (−Ka + √(Ka²+4Ka·C₀))/2.