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Does Alcohol Evaporate? (Yes. It Does)

Does Alcohol Evaporate? (Yes. It Does)

You may have heard of closing deodorant bottles or other alcohol-infused products in order to stop them from evaporating away. At the same time, if you look at alcoholic beverages like vodka or beer, they seem to last a long time even when left open overnight. Hence, the question arises – does alcohol evaporate?

It might not be noticeable, but many things around us contain a percentage of alcohol – disinfectants, removers, cleansers, floor cleaners, etc. You may even want to know what makes the alcohol evaporate, and if there is anything that can be done about it. 

Without further ado, read on to know more!

Does Alcohol Evaporate?

Alcohol evaporates really quickly, and faster than water in a very scientific phenomenon. This happens because the molecules at the top surface have a tendency to break the hydrogen bond and escape. However, the speed of evaporation depends on many factors including the purity of the alcohol, room temperature, humidity, etc. 

When the air pressure above the surface of alcohol is greater than the vapor pressure present at its surface, the molecules rapidly vibrate then leave the liquid and transform into gas molecules. This is how evaporation of the alcohol takes place slowly over time. 

If we were to add water to alcohol and start heating it to evaporate the mixture, we will notice that the alcohol will evaporate first and leave behind water because alcohol has a lesser boiling temperature than water.

Why Does Alcohol Evaporate?

Alcohol evaporates because, at a surface level, the molecules of alcohol come in contact with air. This causes the liquid molecules at the surface to react due to vapor pressure and break their bond with hydrogen which causes it to start evaporating. The evaporation rate of alcohol is even faster than that of water. If you were to add water to a solution of alcohol, the latter will vaporize faster.

The process of evaporation takes place differently for varying types of liquids. One of the main factors affecting evaporation is intermolecular forces or IMFs. They are in charge of maintaining the molecules’ proximity to one another.

In the case of alcohol, the air pressure above a liquid’s surface is higher than the vapor pressure at the surface of a solution. This causes the liquid’s molecules to rapidly vibrate (the fizz you might notice in alcoholic beverages), building up enough energy for the molecular bonds to break and the vapor to escape into the atmosphere. 

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Liquids with lower IMF values have a tendency to evaporate more quickly than those with higher IMF values and those in a solid state have a higher IMF value than those substances in liquid and gaseous states.

man-pouring-alcohol

Factors That Affect Evaporation

Although alcohol is a substance that evaporates naturally, there are other factors that affect how fast it goes through the process. Following are some of the conditions that can directly impact the rate at which alcohol evaporates. 

1. Room Temperature

As a rule of thumb, the temperature of a liquid is equivalent to its evaporation rate. That is to say, at room temperature, the alcohol will probably vaporize slowly and will take a generous amount of time for it to evaporate. 

However, if a solution is heated above room temperature, the liquid’s molecules get more kinetic energy that makes them bubble as well as get the energy needed to break the bond on the surface. The intermolecular forces in liquids weaken as temperature rises and since molecules consequently have a tendency to exit more quickly, the alcohol evaporates faster. 

Another reason alcohol evaporates faster is also that it is a liquid substance and its viscosity allows it to evaporate faster. 

2. Container’s Surface Area

Alcohol also evaporates faster depending on the kind of container it is kept in. The rate of evaporation is also directly proportional to the surface area, just like temperature. When placed in a flat container, most of the molecules will be brought to the surface, where they will be the first to break the bond, and vaporize. 

Compared to that, when in a bottle with only a small space for air to escape, alcohol will remain longer as the molecules will have less of a chance to escape from the liquid solution in such a small area.

3. Humidity Levels

Temperature is an important factor that controls alcohol evaporation. Hence, the outside surroundings of the container also matter. Alcohol is hydrophilic, so if the environment is humid, alcohol will be attracted to the water molecules in the air and evaporate faster. 

Water, on the other hand, evaporates at a slower rate when there is a lot of liquid vapors in the air. Therefore, for the water to evaporate, it is much better if the air is dry. 

4. Speed of The Wind

Since humidity affects the rate of evaporation, the wind, if there is any, also affects how fast the liquid will evaporate. 

The wind not only makes the environment dryer, but it also decreases the chances of the liquid molecules that evaporate going back to their original state and going back into the container. 

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This is because sometimes, the evaporated gaseous molecules go up to the liquid’s surface, and occasionally collide with liquid (at the liquid-air boundary) and turn back into liquid molecules. When there is a high-speed wind, it constantly keeps the surface levels dry. 

What Temperature Does Alcohol Evaporate?

The normal vaporizing point of alcohol is 173°F (78°C). However, it also depends on the surrounding factors, the amount of alcohol, and the type of variant it is. When mixed with water in alcoholic drinks, it will evaporate before the latter which requires around 212°F (100°C) to vaporize. 

When you add alcohol while cooking certain dishes, the alcohol might not even leave completely from the recipe if you use liquor with a higher ABV. This is because simply heating a container will not cause the alcohol to evaporate, and the whole mixture needs to be boiled for the liquid to vaporize. 

According to research done in 2003 by the USDA’s Nutrient Data Laboratory, the amount of alcohol that remains in food can differ depending on the preparation process. Only 5 percent of the initial amount of alcohol is still present in baked recipes or simmered foods. Meanwhile, 85% of the alcohol is still present when it is introduced to a boiling liquid and subsequently removed from the heat.

How Long Does It Take For Alcohol To Evaporate?

The evaporation point for alcohol is different for every variant of its kind. Normal, chemical alcohol will usually take around 2.5 hours to completely evaporate. If you were to leave a bottle of it out in the open, at around 15 minutes, you will see that 40% of alcohol will remain. After 30 minutes, only 35% will stay. After around 2 – 2.5 hours, you might still find it at 5%. This too will differ according to the kind of alcohol you are using.

Keeping in mind the factors that help alcohol evaporate are all equal at a time, different kinds of variants will vaporize at different points. Generally, alcoholic ethanol disinfectants tend to evaporate the fastest, since they have a higher ABV (60  – 70%) and liquor like beer and wine will take longer to vaporize. The higher the ABV, the faster the alcoholic substance evaporates. 

In alcoholic drinks, where water is mixed in the solution, the speed of alcohol evaporation is also different. For example, whiskey might remain overnight due to the numerous ingredients in it, but wine and beer evaporate more quickly. 

Even when used in cooking, different methods will evaporate alcohol faster. Following is a table from the US Department of Agriculture that shows the amount of alcohol  certain dishes will retain according to the method. 

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Cooking MethodAmount Of Alcohol Left
When added to a boiling liquid85%
When flamed75%
Stored overnight with no heat70%
Baked without alcohol being mixed in the batter45%

Does Alcohol Evaporate If You Leave It Open?

Alcohol will evaporate if you leave it open. How fast it evaporates depends on the amount and kind of alcohol you are using. The closer the alcohol is to its pure form, the faster it evaporates – like how disinfectants will vaporize almost immediately and alcoholic beverages take a day or two. It all depends on the alcohol’s potency. Mixed in with substances like water, its vapor pressure is bound to change. 

If pure alcohol is left exposed, airborne water vapor will be absorbed and the alcohol evaporation will be influenced to some extent by this phenomenon.

Does Alcohol Evaporate at Room Temperature?

Alcohol can evaporate at room temperature, but it might take a while depending on its form. For example, isopropyl alcohol, which is close to the pure form, does not stick very well at room temperature as other liquids like water molecules will do. It evaporates within seconds when exposed. Alcoholic beverages, on the other hand, might take days, weeks, or even longer according to their type. 

If you were to tamper with the surface area, airflow, and temperature of the alcohol, you might be able to slow down or hasten the evaporation speed of alcohol. Such liquors usually evaporate faster according to their ABV. Interestingly, wine with a usual ABV of 11% – 12% left to evaporate will likely turn into vinegar before the alcohol content evaporates. 

What Happens If You Leave Alcohol Open?

If you were to leave alcohol open – typically those of principal liquors like vodka, rum, tequila, whiskey, and gin have a tendency to lose some of their flavors over time. They will not rot very quickly and you can easily use an opened bottle of alcohol that is almost past its expiration date without fearing stomach problems. Pure alcohol will simply evaporate at a rapid rate according to the amount.

Remember that the more alcohol there is in the bottle, the faster it shall vaporize. Alcoholic drinks will also change in flavor as they will react with oxygen-rich air, which speeds up oxidation and degradation. 

Final Thoughts 

Hence, we have come to the conclusion that alcohol does evaporate – especially in its purest form. Alcoholic beverages may not evaporate fast, but they will do so after reaching a few hours into the conditions required. We hope that this article has helped you understand the phenomenon better and solved the queries you had.