Free Kb Calculator

Calculate the base dissociation constant (Kb) from equilibrium concentrations of the conjugate acid, hydroxide ion, and undissociated base.

M
M
M

Kb

0.0010

pKb3.00

Kb vs Concentration of Conjugate Acid [BH⁺]

How to Calculate Kb

Formula

Kb = [BH⁺][OH⁻] / [B]

Where:

  • Kb = base dissociation constant
  • [BH⁺] = concentration of conjugate acid at equilibrium
  • [OH⁻] = hydroxide ion concentration at equilibrium
  • [B] = concentration of undissociated base at equilibrium
  • Larger Kb indicates a stronger base.

    Example Calculation

    A 0.1 M ammonia solution has [NH4⁺] = 0.01 M and [OH⁻] = 0.01 M at equilibrium.

    1. 01Kb = [BH⁺][OH⁻] / [B]
    2. 02Kb = (0.01)(0.01) / 0.1
    3. 03Kb = 0.0001 / 0.1
    4. 04Kb = 1.0 × 10⁻³

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