Carbonate

Carbonate, salt of carbonic acid that contains the carbonate ion CO₃=. They are produced by reacting a base, such as metal oxide or hydroxide, with carbonic acid, which is formed by dissolving carbon dioxide in water. Calcium carbonate is very abundant in nature, occurring as limestone, chalk, and marble. The mineral dolomite is a mixture of calcium and magnesium carbonates. Commercially, the most important carbonate is sodium carbonate, also called soda ash and washing soda. Carbonates are decomposed by acids, carbon dioxide being given off. Heating carbonates also drives off carbon dioxide, leaving the metal oxide.