Maxwell construction
= Maxwell construction
{c}
= Maxwell equal-area construction
{c}
{synonym}
At fixed <temperature>, choose a coexistence <pressure> $p_*$ such that the gas and liquid have equal <chemical potentials>. Because $d\mu=v\,dp$, this gives $\int_{v_l}^{v_g}v\,dp=0$, or equivalently $\int_{v_l}^{v_g}[p(v,T)-p_*]\,dv=0$. The equal areas replace the unstable part of an isotherm by a horizontal coexistence segment.