Ka Calculator Formula

Understand the math behind the ka calculator. Each variable explained with a worked example.

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Formulas Used

Ka

ka_value = (h_conc * a_conc) / ha_conc

pKa

pka_value = -log10((h_conc * a_conc) / ha_conc)

Variables

VariableDescriptionDefault
h_conc[H+] at Equilibrium(M)0.004
a_conc[A-] at Equilibrium(M)0.004
ha_conc[HA] at Equilibrium(M)0.096

How It Works

How to Calculate Ka

Formula

Ka = [H+][A-] / [HA]

For the equilibrium: HA <-> H+ + A-

Worked Example

At equilibrium: [H+]=0.004, [A-]=0.004, [HA]=0.096 M.

h_conc = 0.004a_conc = 0.004ha_conc = 0.096
  1. 01Ka = (0.004 × 0.004) / 0.096
  2. 02Ka = 0.000016 / 0.096
  3. 03Ka = 1.67 × 10^-4
  4. 04pKa = -log10(1.67 × 10^-4) = 3.78

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