Using the concept of latent heat, explain why perspiration is an effective way of reducing a person's body temperature

Answer 1

The process of a phase change, such as the evaporation of perspiration from the skin, requires the exchange of energy known as latent heat. As molecules of water escape, or evaporate, from the skin, energy is taken from the environment. During evaporation, the more energetic, faster-moving molecules escape most easily and the average motion of all the molecules left behind decreases as each additional molecule evaporates. Since temperature is a measure of average molecular motion, the slower motion suggests a lower water temperature. Therefore, evaporation is a cooling process because the energy needed to change the water's phase from liquid to a gas is taken from the environment.