Acid Dissociation Constant Calculator

This calculator can be used to determine the acid dissociation constant (Ka) for a weak acid solution based on measured hydrogen ion concentration and initial acid concentration.

Input Parameters

Calculation Results

Calculation Formula

Ka = [H⁺]² / (C - [H⁺])

Where:
Ka = Acid Dissociation Constant
[H⁺] = Hydrogen ion concentration
C = Initial acid concentration

Result

Acid Dissociation Constant (Ka): -

Acid Dissociation Constant Calculator Usage Guide

Learn how to use the Acid Dissociation Constant Calculator and its working principles

How to Use This Calculator

  1. Enter the initial concentration of your weak acid solution in moles per liter (M).
  2. Enter the measured concentration of hydrogen ions [H⁺] in moles per liter (M).
  3. Click the "Calculate" button to compute the acid dissociation constant (Ka).
  4. The result will be displayed in the results section.

Understanding the Acid Dissociation Constant (Ka)

The acid dissociation constant (Ka) is a quantitative measure of the strength of an acid in solution. It indicates how completely an acid dissociates in water. The formula used in this calculator is:

Ka = [H⁺]² / (C - [H⁺])

This formula assumes a weak acid dissociation where the concentration of the undissociated acid (C - [H⁺]) can be approximated as the initial concentration minus the hydrogen ion concentration.

Example Calculation

For example, if you have a 0.1 M solution of acetic acid with a measured hydrogen ion concentration of 0.0013 M, the Ka would be calculated as:

Ka = (0.0013)² / (0.1 - 0.0013) = 1.69 × 10⁻⁵

This matches the known Ka value for acetic acid.

Applications

This calculator is useful in chemistry for:

  • Determining the strength of weak acids
  • Calculating pH from Ka and initial concentration
  • Understanding acid-base equilibrium in solutions
  • Analyzing buffer solutions