Answer:
Sweating has a cooling effect because of the water's high:
c. heat of vaporization.
The high heat of vaporization of water allows it to absorb a significant amount of heat energy from the skin when it evaporates, thereby cooling the body.
Explanation:
Water has a high heat of vaporization, which means it requires a significant amount of energy to change its state from a liquid to a gas. When sweat evaporates from the surface of the skin, it absorbs heat energy from the skin and the surrounding tissues to facilitate the phase change. This process cools down the skin and helps regulate body temperature.
Here's how it works:
1. When the body temperature rises due to physical exertion, high ambient temperatures, or other factors, the hypothalamus in the brain detects this increase.
2. In response, the hypothalamus signals the sweat glands to produce sweat.
3. Sweat is primarily composed of water and contains some electrolytes. As it is secreted onto the skin's surface, it forms a thin layer.
4. When sweat comes into contact with the air, the heat from the skin causes the water molecules in the sweat to gain enough energy to overcome the attractive forces holding them together in the liquid phase.
5. As a result, these water molecules break free and evaporate into the air, carrying away heat energy from the skin.
6. The heat energy transferred to the water molecules during evaporation decreases the temperature of the remaining sweat and the surface of the skin, providing a cooling sensation.
Overall, sweating and subsequent evaporation of sweat help dissipate excess heat from the body, thereby preventing overheating and maintaining a stable body temperature. This cooling mechanism is crucial for thermoregulation and helps prevent heat-related illnesses such as heat exhaustion and heatstroke.
