Sweating has a cooling effect because of water's high __________.

• A. buffering capacity
• B. surface tension
• C. specific heat
• D. heat of vaporization

Answer: (D)

Verified step by step guidance

1. Understand the concept of 'heat of vaporization': This is the amount of energy required to convert a substance from a liquid to a gas at its boiling point. For water, this is particularly high, meaning it takes a lot of energy to vaporize water.
2. Recognize the physiological process: When you sweat, your body releases water onto the skin surface. As this water evaporates, it absorbs heat from your body, effectively cooling you down.
3. Differentiate between the options: 'Buffering capacity' refers to the ability to resist changes in pH, 'surface tension' is the force that causes the surface of a liquid to contract, and 'specific heat' is the amount of heat per unit mass required to raise the temperature by one degree Celsius. None of these directly relate to the cooling effect of sweating.
4. Identify the correct term: The cooling effect of sweating is due to the 'heat of vaporization' of water, which is the energy absorbed during evaporation, leading to cooling.
5. Apply this understanding: Knowing that the 'heat of vaporization' is the correct term helps explain why sweating is an effective cooling mechanism for the body.