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

Key Concepts

Vaporization

Vaporization is the process by which a liquid turns into a gas. For water, this occurs when molecules gain enough energy to overcome intermolecular forces. At 1 atm pressure, water vaporizes at 100°C, but the spontaneity of this process depends on temperature and the Gibbs free energy change.

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 when the change in Gibbs free energy (ΔG) is negative. For vaporization, ΔG can be influenced by temperature, pressure, and the enthalpy and entropy changes associated with the phase transition.

Phase Equilibrium

Phase equilibrium occurs when the rates of vaporization and condensation are equal, resulting in a stable state. At 1 atm, water and steam coexist at 100°C. Above this temperature, vaporization becomes spontaneous as the system favors the gaseous phase, while below it, condensation is favored, indicating the importance of temperature in determining the spontaneity of vaporization.