How does drinking alcohol make your body colder?

Answer 1

Evaporative coolingAny object will absorb heat from its surroundings if the surroundings are warmer than it. Since room temperature is usually lower than body temperature, alcohol is usually colder than your skin. When you put alcohol on your skin, first, your body will warm the alcohol until it is the same temperature as your skin, and that feels a little cold to you (just like when you touch any object at a lower temperature than body temperature, like a piece of metal). However, alcohol feels colder than most objects, right? Why?

It is not this first warming step that actually feels especially cold. It's what happens next. Once warmed up to body temperature, alcohol can evaporate easily (unlike a piece of metal!). As the alcohol evaporates (or any liquid in fact, but alcohol evaporates easily, so it feels more cold than say, water), it goes from a liquid to a gas. The evaporation process takes energy, and that energy goes into breaking apart the liquid alcohol molecules to make isolated alcohol molecules in the gas phase. If it's on your skin, it takes energy from you skin, in the form of heat. If something removes heat from your skin, that feels cold to you. Evaporation is a process that requires a lot of energy, so it can feel quite cold.

Evaporative cooling is an extremely effective method to cool anything (not just skin!), and works for any liquid as long at it is fairly easy to go from a liquid to a gas. For instance, the process of going from a gas to a liquid and back again is how your fridge keeps things cold too (although your fridge doesn't do it with alcohol).

In more technically accurate chemical terms, evaporation is an endothermic process. That means that the process consumes energy. This is because to turn a liquid into a gas, you have to break all of the intermolecular forces that hold that liquid together (these can include Van der Waals foces, dipole-dipole forces, and in the case of an alcohol, hydrogen bonding). Breaking all those attractive interactions requires a lot of energy. When alcohol evaporates on your skin, your body is supplying most of the energy to break all of those intermolecular interactions. Any endothermic reaction will feel cold. When you use one of those instant cold-packs, a special endothermic chemical reaction inside the pack is what makes it so cold suddenly.

Answer 2

The evaporation of a liquid, whether water, alcohol, or any other, consumes a certain amount of energy and therefore has a cooling effect. There is some degree of bonding between molecules of alcohol when they are in a liquid state, that keeps them together, and that bond has to be broken in order for them to be able to expand into the gas phase, and that requires energy.

Answer 3

Alcohol causes increased circulation of blood to your skin, which means more heat carried by your blood is exposed to whatever your touching and thus you cool faster.