Formic acid has a Ka value of .00018. The Ka value is called the acid dissociation constant and is used to measure the acidity of an acid. Formic acid is represented by the chemical formula HCHO2.
The acid dissociation constant measures how the hydrogen from the acid dissociates when the acid is used in an aqueous solution. Strong acids are characterized by full dissociation of the hydrogen atom, while weak acids dissociate less. The pKa is also used to measure acidity and is related to the Ka value as pKa = -log(Ka). Formic acid has a pKa value of 3.77, which means that it is a weak acid.