Figure 5.06. Azeotropic point on the water-ethanol phase diagram. A water-ethanol mixture that is 95.6 weight percent ethanol boils to a vapor of the same composition at 78.17°C. This special solution is called an azeotropic mixture because the boilng point does not change as boiling proceeds. The boling curve and the condensation curve both meet at the azeotropic point (and both have horizontal tangents). Data from Evans (1916). Notice that this diagram shows only the ethanol-rich portion of the water-ethanol phase diagram. To see the full water-ethanol diagram click here:
