In sports competitions, sometimes athletes are suddenly injured. When carrying out first aid, medical staff often spray a fog like medicine on the injured part. If an athlete is not seriously injured, after such emergency treatment, he can often return to the field and stick to the game. What kind of magical medicine is this? Why can it have such a great effect on pain?
Originally, this is an organic substance called chloroethane (c2h5cl). Its boiling point is only 12.3 ℃, so it is a gas at normal temperature and pressure. Usually, it is stored in metal cans with high pressure. Due to the high pressure, the chloroethane in the metal tank is liquid. At the moment of spraying, the pressure drops sharply, and due to contact with warm skin, chloroethane immediately becomes a gas. The transformation of matter from liquid to gas is an endothermic process. Substances absorb a lot of heat from the surrounding environment, which will reduce the surrounding temperature. Chloroethane, which changes from liquid to gas, absorbs a lot of heat from the skin of the injured part of the athlete, which can make the injured part freeze at once, paralyze the nerves, and the pain is relieved quickly.
Chloroethane acts as a local anesthetic. It is used to deal with general muscle contusions or sprains, and can only be used as an emergency measure, because although the pain is temporarily relieved, it can not be treated. At the end of the competition, athletes have to receive formal treatment.