basic

pH of Weak Acid from Ka Calculator

[H⁺] ≈ √(Ka · C₀) → pH for a weak monoprotic acid.

Compute the pH of a weak monoprotic acid solution from its acid-dissociation constant Ka and its analytical (initial) concentration C₀, using the customary [H⁺] ≈ √(Ka · C₀) approximation. Reports both pH and percent dissociation.

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 · C₀); pH = −log₁₀[H⁺]; α = [H⁺] / C₀.

In depth

Compute the pH of a weak monoprotic acid solution from its acid-dissociation constant Ka and its analytical (initial) concentration C₀, using the customary [H⁺] ≈ √(Ka · C₀) approximation. Reports both pH and percent dissociation.