ropanoic acid and ethanol react to produce ethyl propanoate and water. The ester link is formed by the reaction of a hydroxyl group with a carboxyl group.
The reaction of an alcohol with a carboxylic acid is a reversible reaction. In the reaction, some of the ester molecules formed are split up again into the alcohol and carboxylic acid they are made from. This happens when water reacts with the ester link. This is a hydrolysis reaction.