According to the kinetic molecular theory, which of the following states of water contains particles with the highest average kinetic energy?

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

Answer: (B)

Verified step by step guidance

1. Recall that according to the kinetic molecular theory, the average kinetic energy of particles is directly proportional to the temperature of the substance, regardless of its state (solid, liquid, or gas).
2. Understand that kinetic energy is related to temperature by the equation \(KE_{avg} = \frac{3}{2} k_B T\), where \(k_B\) is the Boltzmann constant and \(T\) is the absolute temperature in kelvins.
3. Recognize that water vapor (gas phase) typically exists at a higher temperature or has more energetic particles compared to liquid water or ice at the same conditions, because gases have particles moving more freely and rapidly.
4. Compare the states: ice (solid) has particles vibrating in fixed positions with the lowest kinetic energy, liquid water has particles moving more freely with moderate kinetic energy, and water vapor (gas) has particles moving fastest with the highest kinetic energy.
5. Conclude that among the given states, water vapor contains particles with the highest average kinetic energy due to their greater freedom of movement and higher temperature.