Which statement correctly describes the relationship between the enthalpy of vaporization and the enthalpy of condensation for a substance?

• A. The enthalpy of condensation and vaporization are identical in both magnitude and sign.
• B. The enthalpy of condensation is unrelated to the enthalpy of vaporization.
• C. The enthalpy of condensation is equal in magnitude but opposite in sign to the enthalpy of vaporization.
• D. The enthalpy of condensation is always greater than the enthalpy of vaporization.

Answer: (C)

Verified step by step guidance

1. Understand that enthalpy changes (\( \Delta H \)) represent the heat absorbed or released during a process at constant pressure.
2. Recall that vaporization is the process of a liquid turning into a gas, which requires energy input, so the enthalpy of vaporization (\( \Delta H_{vap} \)) is positive.
3. Recognize that condensation is the reverse process, where a gas turns into a liquid, releasing energy, so the enthalpy of condensation (\( \Delta H_{cond} \)) is negative.
4. Since condensation is the exact reverse of vaporization, the magnitude of the enthalpy change is the same, but the sign is opposite, meaning \( \Delta H_{cond} = - \Delta H_{vap} \).
5. Therefore, the correct relationship is that the enthalpy of condensation is equal in magnitude but opposite in sign to the enthalpy of vaporization.