This Demonstration plots the vaporliquid isobaric diagram and equilibrium curve at low to moderate pressures for a binary mixture of acetic acid and water Deviation from ideal behavior in the liquid phase is considered using the Wilson model Gasphase dimerization of acetic acid is also taken into account The dimerization equilibrium constant was taken from G Venimadhavan M Malone and M Doherty Bifurcation Study of Kinetic Effects in Reactive Distillation AIChE Journal 453 1999 pp 546–556 where is the temperature in Kelvins The bubblepoint and dewpoint curves are represented in red and green respectively The equilibrium curve is show in blue