Consider the vaporization of liquid water to steam at a pressure of 1 atm. (c) In what temperature range is it a nonspontaneous process?

Key Concepts

Gibbs Free Energy

Gibbs Free Energy (G) is a thermodynamic potential that helps predict the spontaneity of a process at constant temperature and pressure. A process is spontaneous if the change in Gibbs Free Energy (ΔG) is negative. For the vaporization of water, understanding how temperature affects ΔG is crucial in determining the conditions under which the process becomes nonspontaneous.

Phase Equilibrium

Phase equilibrium refers to the state where the rates of vaporization and condensation of a substance are equal, resulting in no net change in the amount of liquid and vapor. At 1 atm, water vaporizes at 100°C. Below this temperature, the equilibrium shifts towards the liquid phase, indicating that vaporization is nonspontaneous as the system favors condensation.

Clausius-Clapeyron Equation

The Clausius-Clapeyron equation describes the relationship between the pressure and temperature of a substance during phase changes. It provides insight into how the vapor pressure of water changes with temperature, which is essential for understanding the conditions under which vaporization occurs. This equation helps identify the temperature range where vaporization is nonspontaneous by relating it to the pressure of the system.