Which of the following actions would most effectively increase the effectiveness of evaporative cooling?

• A. Add salt to the liquid to raise its boiling point
• B. Reduce the airflow over the liquid surface
• C. Decrease the temperature of the surrounding air
• D. Increase the surface area of the liquid exposed to air

Answer: (D)

Verified step by step guidance

1. Understand the principle of evaporative cooling: it occurs when molecules with higher kinetic energy escape from the liquid surface, lowering the average kinetic energy and thus the temperature of the remaining liquid.
2. Recognize that increasing the surface area of the liquid exposed to air allows more molecules to escape simultaneously, enhancing the rate of evaporation and therefore the cooling effect.
3. Analyze why adding salt to raise the boiling point would not increase evaporative cooling: raising the boiling point generally decreases vapor pressure, reducing evaporation rate.
4. Consider the effect of reducing airflow: less airflow slows the removal of vapor molecules from the surface, decreasing evaporation and cooling efficiency.
5. Note that decreasing the temperature of the surrounding air reduces the vapor pressure gradient, which can slow evaporation, making it less effective for evaporative cooling.