Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

What is the definition of heat of vaporization?

1. The amount of energy required to change a solid to a liquid

2. The amount of energy required for liquid at its boiling point to become a gas

3. The energy needed to raise the temperature of a liquid

4. The energy needed to freeze a substance

The correct answer is: The amount of energy required for liquid at its boiling point to become a gas

The heat of vaporization is specifically defined as the amount of energy required for a liquid to transform into a gas at its boiling point. This process entails overcoming the intermolecular forces that hold the liquid molecules together, allowing them to disperse into the gaseous phase. During vaporization, the temperature remains constant as the substance absorbs the necessary energy to facilitate the phase change, rather than increasing in temperature. In contrast, the other definitions provided relate to different phase changes or energy requirements. For instance, the transition from a solid to a liquid characterizes the heat of fusion, while raising the temperature of a liquid pertains to specific heat capacity. The energy needed to freeze a substance references the release of energy during the solidification process, which is not related to vaporization. Understanding these distinctions is crucial to grasping the thermodynamic concepts associated with phase changes in matter.