Which of the statements A–D is false?

Question

A. If the molar Gibbs free energy (G) of a substance in the liquid phase is 10 J/mol and the molar Gibbs free energy of the vapor phase is 100 J/mol, then the liquid phase is more stable than the vapor phase.
B. The Clapeyron equation can be used for any phase change, not just liquid to vapor.
C. When 10 kg of liquid water is in equilibrium with 90 kg of water vapor, the Gibbs free energy (GL) of the liquid phase is equal to the Gibbs free energy (GV) of the vapor phase.
D. The Clausius-Clapeyron equation is not applicable to solid-liquid equilibrium.
E. All of the statements above are true.

Answer 1

A. Incorrect. This is true. We could also calculate the molar Gibbs free energy of the solid phase at these conditions. If it is lower than that of the liquid phase, it will be present instead of liquid.
B. Incorrect. This is true. Review Equations 8.23, 8.24 and 8.25.
C. Correct. If two phases are in equilibrium, their molar Gibbs free energies (G) are equal, but because the numbers of moles in the two phases are not equal, the total Gibbs free energies (G) are not equal.
D. Incorrect. This is true. Assumptions 2 and 3 for Equation 8.26 are specific to the vapor phase alone and cannot be reused to derive the same equation for solid-liquid equilibrium.
E. Incorrect. One of the statements is false.