Solid–liquid and gas–solid equilibrium
When solids
join the equilibrium.
Explore melting, eutectics and sublimation. Supply your own properties, identify the stable phases and check how much of each phase can exist.
SLE: liquid and two pure solids Fusion properties and the liquidus
gS,i/(RT) = −ΔHfus,i/R (1/T − 1/Tm,i)
The reference is the pure, possibly supercooled liquid at the same temperature. Each solid contains only its own component. The model checks supporting tangents against the liquid curve and both solid endpoints. The plotted liquidus includes stable branches only. Teal curves use an ideal liquid; amber curves use the selected liquid model.
At the eutectic, liquid and both solids can coexist. T, P and overall composition do not fix all phase fractions. The reported family endpoints describe the full feasible interval; an energy constraint is needed to select an amount. Pure-component melting has the same undetermined fraction issue.
No solid solutions, polymorphs, compounds, vapor, fusion heat-capacity corrections or coupled LLE/SLE are included. Constant liquid parameters are a teaching assumption, not a temperature-dependent fit.
GSE: finite solid inventory Partial pressure is not total pressure
nV = min[nTotal, Psub V/(RT)]
pvolatile = nV RT/V; Ptotal = (nV + nInert)RT/V
ΔA/(RT) = nV[ln(nV/nSat) − 1] + constant
While solid remains, the volatile partial pressure equals the sublimation pressure. If the inventory is exhausted, the gas may be undersaturated. Adding inert ideal gas at fixed T and free gas volume changes total pressure, but not the equilibrium volatile amount.
The free gas volume is fixed; solid volume is neglected. Sublimation enthalpy is constant, gas fugacity is its partial pressure, and condensed-phase pressure corrections are neglected. Both calculated total pressure and sublimation pressure must be at most 200 kPa; this teaching limit does not guarantee ideal-gas accuracy. Supply a source-valid temperature interval that excludes melting and solid transitions. This is phase equilibrium, not a reactive gas–solid equilibrium or adsorption model.