| − | Acidity is frequently expressed as the Acid Value, which is the number of mg of potassium hydroxide required to neutralize the free acids in 1.0 g of the substance.[2] | + | Acidity is frequently expressed as the Acid Value, which is the number of mg of potassium hydroxide required to neutralize the free acids in 1.0 g of the substance.<ref>Pharmacopedia/National Formulary. US., Vol. 1, 2009, p. 150</ref> |