Acidity constant, Ka

Definition

The acidity constant, Ka, measures the strength of an acid in a solution by quantifying its tendency to donate a proton (H+) to a base. It is expressed as the equilibrium constant for the dissociation of the acid into its conjugate base and a proton in water.

Related terms

pH:

A scale used to specify how acidic or basic a water-based solution is, based on the concentration of hydrogen ions present.

pKa:

The negative logarithm of the acidity constant (Ka), providing a more convenient way to express acid strength; lower pKa values indicate stronger acids.

Conjugate base:

The species that remains after an acid has donated a proton during a chemical reaction, often participating in the reverse reaction to reform the acid