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Acidity Constant (Ka) Calculator

Formula

The formula to calculate the Acidity Constant (Ka) is:

$K_a = \frac{[H^+][A^-]}{[HA]}$

Where:

$K_a$ is the acidity constant
$[H^+]$ is the concentration of hydrogen ions in moles per liter (M)
$[A^-]$ is the concentration of the conjugate base in moles per liter (M)
$[HA]$ is the concentration of the weak acid in moles per liter (M)

Definitions

Acidity Constant (Ka): A quantitative measure of the strength of an acid in solution. It is the equilibrium constant for the dissociation of a weak acid into its conjugate base and a hydrogen ion.
Concentration of Hydrogen Ions ([H+]): The concentration of hydrogen ions in the solution.
Concentration of Conjugate Base ([A–]): The concentration of the conjugate base in the solution.
Concentration of Weak Acid ([HA]): The concentration of the weak acid in the solution.

Example

Let's say the concentration of hydrogen ions ([H+]) is 0.01 M, the concentration of the conjugate base ([A–]) is 0.02 M, and the concentration of the weak acid ([HA]) is 0.1 M. Using the formula:

$K_a = \frac{0.01 \times 0.02}{0.1}$

We get:

$K_a = 0.002$

So, the acidity constant (Ka) is 0.002.