... availability of energy in a system for conversion to useful work. In order for a system to perform work, it must have the capacity for spontaneous change toward equilibrium. For instance, a system comprising ... the transformation of energy from one form to another, such as the transformation ofinternal energy to useful work. In this regard, thermodynamics is more general than mechanics in itsformulation ... Thus,(dni)α=−(dni)bHence, the condition for phase equilibrium, along with the requirement of uniformity of temperatureand pressure, is the equality of the chemical potential for each component in both phases:(µi)α=...