Abstract:

Isothermal cycle is a classical method to solve thermodynamic problems in physical chemistry textbooks. In this paper, it is pointed out that The Gibbs free energy change of the reversible phase transformation of the droplet into the gas should be given by the criterion in the method. The Gibbs free energy criterion at constant temperature, gas and liquid pressures can be proven based on the basic principles of thermodynamics. At the same time, a new model and a new understanding of the isothermal cycle method are put forward, which is more straightforward, and thus suitable for teaching.

Key words: Kelvin formula, Isothermal cycle, Gibbs free energy criterion, New model