What is the heat of vaporization?

The heat of vaporization is defined as the amount of energy required to convert a unit mass of a liquid into a gas at its boiling point, without any change in temperature. This process involves breaking the intermolecular forces that hold the liquid molecules together, allowing them to escape into the gaseous phase.

Choosing the correct answer reflects an understanding of phase changes in substances and the specific energy requirements associated with these transformations. The heat of vaporization is significantly higher than the energy required to raise the temperature of a substance or to freeze it, as it requires overcoming the attractive forces between molecules in the liquid state.