For a one-component system, at the triple point

Question

Quizplus · Accepted Answer

At the triple point, all three phases (solid, liquid, and gas) coexist in equilibrium. According to the phase rule, $f = C - P + 2$, where $f$ is the number of degrees of freedom, $C$ is the number of components, and $P$ is the number of phases. For a one-component system ($C = 1$) at the triple point ($P = 3$), $f = 1 - 3 + 2 = 0$. This means there is no freedom to change the conditions (temperature or pressure) without changing the number of phases present.

For a One-Component System, at the Triple Point