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During the transformation of liquid water to water vapor at 100°C and standard atmospheric pressure, which of the following is accurate?

1. The entropy of the system increases, and the entropy of the surroundings increases.
2. The entropy of the system increases, and the entropy of the surroundings decreases.
3. The entropy of the system decreases, and the entropy of the surroundings increases.
4. The entropy of the system decreases, and the entropy of the surroundings decreases.

Correct answer: The entropy of the system increases, and the entropy of the surroundings decreases.

Solution

When water vaporizes at 100°C, the system's entropy increases because the molecules transition from an ordered liquid state to a more disordered gaseous state. However, the surroundings lose heat (enthalpy) during this endothermic process, causing their entropy to decrease.

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