1.2g of p-aminobenzoic acid and 12 ml of ethanol were put together and swirled till homogenous. 1ml of concentrated sulfuric acid was added in drops while the mixture was still being stirred. The round bottom flask was placed on a heating mantle, attached to a reflux condenser, and a magnetic stirring bar was placed in it for occasional stirring. After an hour, the flask was removed from the set up and left to cool. Then the mixture was poured into 30ml of water in a beaker. When the mixture had cooled down, 10ml of sodium carbonate solution was added in drops to the mixture. The gas which was meant to evolve didn’t and also, no precipitation occurred. This lead to continuous addition of the sodium carbonate but nothing still happened.

Please, what are the possible sources of error for this?