Chemical Potential & Fugacity
Van der Waals gas: phase coexistence, Maxwell construction & fugacity
VdW Gas Parameters
Temperature T/Tc:
0.85
Van der Waals a:
1.0
Van der Waals b:
0.333
Show Maxwell
Show Fugacity
Tc (critical T)
2.67
Pc (critical P)
1.00
Vc (critical V)
1.00
Coexist P
—
Fugacity f
—
VdW:
(P + a/V²)(V − b) = RT. Critical point: Tc = 8a/27Rb, Pc = a/27b², Vc = 3b. Below Tc: S-curve unphysical — Maxwell equal-area construction finds coexistence. Fugacity: f = P·exp(∫(1/RT)(V−RT/P)dP) measures effective pressure. At coexistence, μ_liquid = μ_vapor (equal fugacity).