sodium bicarbonate (NaHCO3) Sodium bicarbonate , also known as baking soda, is used to relieve heartburn, sour stomach, or acid indigestion by neutralizing excess stomach acid. When used for this purpose, it is said to belong to the group of medicines called antacids. It may be used to treat the symptoms of stomach or duodenal ulcers 144-55-8 sodium bicarbonate (NaHCO3), white crystalline or powdery solid that is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as a constituent of dry-chemical fire extinguishers.