ICE Table Equilibrium Calculator
Solve weak acid and weak base equilibrium using the ICE table method.
Calculate pH, percent ionization, and equilibrium concentrations from Ka or Kb.
What Is an ICE Table?
An ICE table is a systematic method for solving chemical equilibrium problems. ICE stands for Initial, Change, Equilibrium — the three rows of the table.
Weak Acid Dissociation: HA ⇌ H⁺ + A⁻
| Species | Initial | Change | Equilibrium |
|---|---|---|---|
| HA | Cₐ | −x | Cₐ − x |
| H⁺ | 0 | +x | x |
| A⁻ | 0 | +x | x |
The equilibrium expression is: Ka = [H⁺][A⁻] / [HA] = x² / (Cₐ − x)
Rearranging: x² + Ka·x − Ka·Cₐ = 0
Solving the quadratic formula: x = (−Ka + √(Ka² + 4·Ka·Cₐ)) / 2
Then: pH = −log₁₀(x)
Weak Base: B + H₂O ⇌ BH⁺ + OH⁻
The same method applies using Kb. x = [OH⁻], then pOH = −log₁₀(x), then pH = 14 − pOH.
Percent Ionization
% Ionization = (x / Cₐ) × 100%
Weaker acids have lower Ka and lower percent ionization. Diluting a weak acid actually increases percent ionization (Le Chatelier’s principle).
Common Ka Values
| Weak Acid | Ka |
|---|---|
| Acetic acid | 1.8 × 10⁻⁵ |
| Carbonic acid | 4.3 × 10⁻⁷ |
| Hydrofluoric acid | 7.2 × 10⁻⁴ |
| Ammonium ion | 5.6 × 10⁻¹⁰ |
| Hypochlorous acid | 3.0 × 10⁻⁸ |
5% Approximation Rule
If percent ionization is less than 5%, you can simplify Cₐ − x ≈ Cₐ. This gives x ≈ √(Ka × Cₐ) — a much faster calculation. This calculator always uses the exact quadratic formula for accuracy.