Question

On a hot day, you sweat to maintain your body temperature. Explain how the evaporation of sweat helps remove heat from your skin.

Answer 1

Evaporation of water from the skin surfce helps to convert water in a liquid form to the vapor state by absorbing the heat from the skin. This heat that is being absorbed by water is called the heat of vaporization. As the water absorbs more heat it changes from liquid to gas form and the area of sweat feels cool as the body temperature is reduced. Heat of vaporization is  540 calories/gram, so if a person produces say 100gms of sweat then a total of 540*100= 54000 calories of heat will be removed as sweat evaporates.  

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