Benzoic acid has a Ka value of 6.4 x 10^–5. The Ka value of an acid is known as the acid dissociation constant, and it is a measure of how much a substance ionizes when added to a solution.
The pKa value of benzoic acid is 4.2. The pKa value is related to the acid dissociation constant through the formula pKa = -log(Ka). An acid with a pKa value greater than -2, such as benzoic acid, is considered a weak acid, meaning that it does not dissociate fully. Benzoic acid is written with the chemical formula C7H6O2 and has a molar mass of about 122.12 grams per mole.