For the vaporization of water in an open system at 25°C and 1 atm, which of the following is correct?
A) The reaction is entropy driven.
B) The reaction is enthalpy driven.
C) The reaction is not spontaneous.
D) ΔG°rxn = 0

Question

Quizplus · Accepted Answer

The vaporization of water at 25°C and 1 atm is an entropy-driven process because the change in entropy (ΔS) for the system is positive. The molecules in the liquid phase have more freedom of movement and entropy than in the highly ordered and structured solid phase, allowing for more disorder during the phase change to gas. The enthalpy change (ΔH) for the reaction is also positive, meaning that energy is required to break the intermolecular bonds holding the liquid together to form vapor. However, since the reaction is occurring in an open system, there is no pressure difference to drive the reaction towards the gas phase, making the reaction non-spontaneous. Therefore, ΔG°rxn is positive, indicating that the reaction is non-spontaneous under standard conditions.

For the Vaporization of Water in an Open System at 25°C