Do Ethanol and Water Form an Azeotrope?

The most common example is the azeotrope between water and ethanol (grain alcohol). Water boils at 100 ºC and ethanol boils at 78.3 ºC. The mixture will boil at 78.2 ºC and have a composition of 95% ethanol and 5% water by volume. This is a binary azeotrope because it involves two components.

Is ethanol and water azeotrope?

A well-known example of a positive azeotrope is 95.63% ethanol and 4.37% water (by mass), which boils at 78.2 °C. Ethanol boils at 78.4 °C, water boils at 100 °C, but the azeotrope boils at 78.2 °C, which is lower than either of its constituents.

Why does water and ethanol form an azeotrope?

In the example of the water:ethanol azeotrope, the water is able to increase the amount of hydrogen bonding between ethanol molecules by increasing the density of hydrogen bond donors and acceptors per unit volume.