The reaction for Na2CO3, sodium carbonate, and HCl, hydrochloric acid, is 2HCl + Na2CO3 -> 2NaCl + CO2 + H2O. Two moles of hydrochloric acid and one mole of sodium carbonate form two moles of salt, one mole of carbon dioxide and one mole of water in an irreversible reaction.
Sodium carbonate, also known as soda ash and washing soda, is a naturally occurring base that takes the form of a solid white powder. Hydrochloric acid is found in the stomach, and one of its many uses is to remove metal deposits. If both of the substances are concentrated when they react, their reaction is extremely vigorous.