Which of the following substances would have the highest temperature under standard atmospheric conditions?

• A. Ice water
• B. Liquid water
• C. Water vapor

Answer: (C)

Verified step by step guidance

1. Understand that temperature under standard atmospheric conditions refers to the temperature at which each substance exists in equilibrium at 1 atm pressure.
2. Recall the phases of water at 1 atm: ice water (solid-liquid equilibrium) is at 0°C, liquid water is typically around 25°C (room temperature), and water vapor (gas phase) is at 100°C when in equilibrium with liquid water.
3. Recognize that water vapor at 1 atm pressure corresponds to the boiling point of water, which is higher than the melting point (ice water) and typical liquid water temperature.
4. Compare the temperatures associated with each phase: ice water at 0°C, liquid water around 25°C, and water vapor at 100°C under standard atmospheric pressure.
5. Conclude that water vapor has the highest temperature among the given substances under standard atmospheric conditions because it exists at the boiling point of water.