Gibbs phase ruleGibbs phase rule
A rule stating that the number of degrees of freedom in a closed physical system at equilibrium is equal to the number of chemical components minus the number of phases plus the constant 2. For example, the system of water vapor, liquid water, and solid ice has zero degrees of freedom because the three phases of vapor, liquid, and solid coexist in the one component, water. Also called phase rule .
Origin of Gibbs phase ruleAfterJosiah Willard Gibbs