What causes alcohol to freeze?

Answered by Douglas Hiatt

Alcohol, in its pure form, is a chemical compound called ethanol. Ethanol has a freezing point of -173 degrees Fahrenheit (-114 degrees Celsius). This means that in order for pure ethanol to freeze, it needs to be exposed to extremely low temperatures.

However, when we talk about alcoholic beverages like vodka, they are not pure ethanol. Vodka is typically made by distilling fermented grains or potatoes, resulting in a mixture of ethanol and water. The freezing point of a liquid is determined by its composition, and the presence of water in vodka significantly affects its freezing point.

The freezing point of vodka is around -16 degrees Fahrenheit (-27 degrees Celsius) when it contains about 40 percent alcohol or is 80 proof. This is much higher than the freezing point of pure ethanol due to the water content. Water has a freezing point of 32 degrees Fahrenheit (0 degrees Celsius), and the presence of water molecules in the vodka raises the overall freezing point of the mixture.

When you put vodka in a typical household freezer, which is usually set to around 0 degrees Fahrenheit (-18 degrees Celsius), it will certainly get colder than the freezing point of vodka. As a result, the vodka will be affected by the cold temperature and may become thicker or slushy, but it won’t freeze solid like water does.

The reason for this is that alcohol and water form an azeotropic mixture, which means that they have a unique composition that cannot be separated by simple distillation. This is why vodka won’t freeze solid in a regular freezer, even though its freezing point is higher than the temperature at which most freezers are set.

It’s worth noting that the exact freezing point of vodka can vary depending on its alcohol content. Vodka with a higher alcohol percentage will have a lower freezing point, while lower-proof vodka will have a higher freezing point. However, most commercially available vodkas have a similar alcohol content, so their freezing points will be relatively consistent.

The freezing point of pure ethanol is much lower than that of vodka due to the presence of water. Vodka won’t freeze solid in a regular freezer because its freezing point is higher than the temperature at which most freezers are set. So, while putting vodka in the freezer will affect its consistency, it won’t turn into a solid block of ice.