Is Na2CO3 an Acid or a Base?

Na2CO3, or sodium carbonate, is a base. The compound is commonly known as soda ash in its anhydrous form or washing soda in its hydrated form.

The formation of sodium carbonate involves the reaction of sodium hydroxide and dissolved sodium hydrogen carbonate. When the solution is heated and evaporated, hydrated crystals of sodium carbonate are produced, also referred to as washing soda. Removing the water from the crystals by the application of heat yields the anhydrous form of sodium carbonate, known as soda ash.

There are various practical applications of sodium carbonate in the chemical industry. Washing soda is used to soften "hard" water by extracting insoluble carbonates. Soda ash is an important component in soaps, detergents and other household cleaning products. It is also used in processing petroleum and in the production of glass, rayon and paper.