oxyacid, Any oxygen-containing acid that is usually formed from the reaction of a nonmetal oxide with water. Sulfuric acid is produced in large quantities worldwide for use in making fertilizers, refining petroleum, and removing impurities from kerosene and gasoline. The oxyacid sodium hydrogen carbonate is used to make sodium bicarbonate, or baking soda, and hydrogen carbonate salts, formed from carbonic acid, are strong bases that are widely used in antacids. Other well-characterized oxyacids include nitric acid, nitrous acid, and phosphorous acid.