Sodium carbonate is an inorganic chemical compound. Sodium carbonate is what is commonly known as Soda ash. The compound is basic in nature.
Used as antacid
Sodium hydrogen carbonate is basic. It reacts with excess acid in the stomach and neutralises it. Substances such as sodium hydrogen carbonate are used as antacids because when we use an excess of sodium carbonate, the stomach gets alkaline which further induces the production of acids. Therefore, we use sodium hydroxides which are insoluble, and they do not increase pH value above neutrality.