Acyl chloride reaction with water. Demonstration of the reaction between an acyl chloride (in this case ethanoyl chloride, CH3.COCl) and water (H2O). The pipetted addition of ethanoyl chloride to the water in the beaker has formed ethanoic acid (CH3.COOH) and fumes (white) of hydrochloric acid, formed as hydrogen chloride (HCl) reacts with water in the air. This is an addition-elimination reaction that sees a hydroxide (OH) group added to the ethanoyl chloride from a water molecule, and a hydrogen chloride (HCl) molecule being eliminated. An ammonia-soaked (NH3) glass rod tests for HCl by forming white fumes of ammonium chloride (NH4Cl).