Sodium Carbonate Formula

Sodium carbonate is the inorganic compound with the formula $Na_2CO_3$. It exists in both hydrous and anhydrous forms. It is a white, odourless salt that yields alkaline solutions in water. It is also a moderately strong base that can be used as a cleaning agent. It is manufactured by many methods, but the most famous one is the Solvay process. It was originally extracted from the ashes of plants grown in sodium-rich soils.

The anhydrous form is the powder that you find in chemical supply stores, swimming pool shops and hardware stores. It has no water molecules in the crystals, but it is hygroscopic and will absorb a little water from the air. If you store it in a dessicator it will remain dry, but if you keep it open for long it will absorb water and turn into a decahydrate. This is the form that is sold as washing soda. It is the most common use for sodium carbonate.

It is also used as a pH adjuster, anti-caking agent and manufacturing aid for applications like glass making where it acts as a flux to lower melting temperatures. It is also used as a food additive, water softener and in taxidermy.

Baking soda (sodium bicarbonate) is NaHCO3, and chalk (calcium carbonate; CaC2O3) and paris white or plaster of paris (calcium sulfate; CaSO42) are all derived from natural minerals that have been mined from the ground or retrieved from lake brines.