Why liquid ammonia bottles are cooled before opening the seal?
Ammonia is a liquid at ordinary temperature under high pressure. If the seal of the bottle is opened without cooling the bottle first, the liquid ammonia will vaporise and come out of the bottle with force. This may either cause the breaking of bottle or accident. Cooling the bottle under tap water reduces the temperature and hence the pressure. Consequently, on opening the seal, the chance of any accident gets reduced.