Chilling vodka enhances the drink's smooth texture, letting it coat the mouth while still preserving most of the drink's character, according to Belvedere Vodka's Claire Smith. To this end, many vodka lovers will put their vodka in the freezer for a short time. Despite the low temperature, the liquor will not actually freeze. Although it is possible to freeze 80-proof vodka (the standard for unflavored vodka), it requires temperatures lower than those in a home freezer.
Ethyl alcohol, usually called ethanol, is the type of alcohol found in alcoholic beverages. The freezing point of ethanol is much lower than that of water; while water freezes at 32 Fahrenheit (0 C), ethanol freezes at -174.6 F (-114.7 C). This results from the different molecular structures of the two substances. Water molecules form naturally into a solid structure, while the attraction between ethanol molecules is much lower.
A Matter of Concentration
Although ethanol freezes at -174.6 F, this isn't the freezing point of vodka. A solution of ethanol and water will have a freezing point between the two, depending on the concentration of ethanol in the solution. Unflavored vodka is typically 80 proof, or 40 percent alcohol by volume. Governors State University's analytical chemistry blog puts the freezing point of 80 proof vodka at -16.5 F (-27 C).
Cold, But Not Cold Enough
The temperature in a home freezer can vary, but most are in the vicinity of 3 degrees F (-16.1 C). This is significantly higher than the freezing point of vodka; as a result, complete freezing of 80-proof vodka is essentially impossible in a home freezer. There are conditions under which vodka can freeze; for instance, immersion in a bath of dry ice in isopropyl alcohol will freeze solutions of up to 90 percent ethanol. However, this type of freezing bath is dangerously cold and usually only found in laboratories.
Because the freezing point of water is higher than the freezing point of ethanol, some of the water in the solution may freeze out before the solution (in this case, the vodka) freezes. However, the point at which this occurs is still below the freezing point of water; this is because of the way in which the ethanol molecules prevent water molecules from aligning into a solid structure. This type of "fractional freezing" has been used to produce concentrated alcohol in cold climates for centuries.
- Complex City Guide: Should You Freeze Vodka?
- Scifun: Ethanol
- North Carolina State University: Why Does Water Freeze Before Alcohol Does?
- Analytical Chemistry: Why Doesn't Vodka Freeze?
- Popular Science: How to Make Strong Beer Stronger
- The Daily Green: Check the Temperature in Your Fridge and Freezer
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