Under typical room-temperature conditions (i.e., roughly 70 degrees via moderate humidity), if I were to leave a glass containing, say, a liquid that was 5% alcohol by volume, would the alcohol evapoprice much faster than the water? Would this answer change depending upon whether the liquid was simply ethanol and also water vs. if it had actually various other ingredients in the solution (e.g., wine)? Thanks!


Not a chemist, yet I think the answer is yes. Alcohol feels cool on the skin because of fast evaporation.

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I think the answer would certainly be uncovered in the vapor pressure numbers. According to a chart here for water, the vapor push at 20 C is 2.34 kPa, while the similar chart for ethanol mirrors a vapor pressure of about 5.3 kPa at 19 C.

So tbelow needs to be more than twice as a lot ethanol in the air as water under equivalent problems for the air to be saturated. Which I'm pretty sure indicates that ethanol will certainly evaporate more conveniently, though I don't recognize the specific equation for rate of evaporation.

Oh, likewise ethanol boils at 78 C compared to water at 100 C, which I'm sure contributes. It's closer to the boiling suggest than water is at room temperature.

You think right! In significance vapor pressure is really what determines the boiling point in the initially place, as soon as the equilibrium vapor push (which is a role of temperature) of a liquid matches the in its entirety pressure of the system (say 1 atmosphere) it will boil. For instance, the vapor push of water hits 1 atm at 100 C, so it boils.

This isn’t a peer reregarded post but inspect this web page out if your interested in learning a bit more about it: https://www.chem.purdue.edu/gchelp/liquids/vpress.html

Yes - there's a pair of things that make a difference.

The boiling point of ethanol is lower than that of water so more molecules of ethanol will have enough power to escape the liquid and also rush off into the air as a gas than molecules of water. With time this adds up and more of the ethanol will certainly evapoprice than the water. This indicates beer gets weaker as it's left out.

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Another amazing point is that ethanol will certainly actually gather at the water surface. Not every one of it, but some. I'm not saying that the surconfront of your beer is noticeably even more alcoholic yet the exceptionally surchallenge of the liquid will certainly have actually a surplus of ethanol molecules. This is bereason water hates air - this is why droplets are so round, to reduce the amount of surconfront for a offered volume - and ethanol has actually one finish (OH) that gets on well via water and also an additional finish that doesn't really treatment too much what it is pointed towards (CH3CH3). The reality that ethanol gathers at the surchallenge could actually aid even more ethanol evapoprice over time compared through water!

Interestingly if you were to take an alcohol with a really lengthy CH chain at the finish prefer dodecanol and also spread that at the surchallenge it could actually sheight the water evaporating all together - it can create a film over the height and also stop water escaping while the dodecanol molecules are as well much from their very own boiling point to evaporate themselves.