# How quickly does alcohol in liquor in a glass evaporate?

**URL:** <https://boards.straightdope.com/t/how-quickly-does-alcohol-in-liquor-in-a-glass-evaporate/562137>\
**Category:** Factual Questions\
**Created:** [November 28, 2010, 2:47am UTC](https://boards.straightdope.com/t/how-quickly-does-alcohol-in-liquor-in-a-glass-evaporate/562137 "2010-11-28T02:47:36Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![janebob77](https://avatars.discourse-cdn.com/v4/letter/j/6f9a4e/32.png) [@janebob77](https://boards.straightdope.com/u/janebob77)\
**Post date:** [November 28, 2010, 2:47am UTC](https://boards.straightdope.com/t/how-quickly-does-alcohol-in-liquor-in-a-glass-evaporate/562137/1 "2010-11-28T02:47:36Z")

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If I pour a glass of 100 proof liquor in a glass and let it sit on the counter for an hour, is it still 100 proof (or 50%) alcohol when I return? What is the rate of evaporation of the alcohol?

Thanks

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**Author:** ![AmunRa](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AmunRa](https://boards.straightdope.com/u/AmunRa)\
**Post date:** [November 28, 2010, 3:12am UTC](https://boards.straightdope.com/t/how-quickly-does-alcohol-in-liquor-in-a-glass-evaporate/562137/2 "2010-11-28T03:12:13Z")

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[This site](http://bayblab.blogspot.com/2009/01/evaporation-rates-of-ethanol-solutions.html) demonstrates that ethanol does evaporate at a greater rate than water in solution. However, their tests are over a one week period, and the difference over one weeks looks small enough to me that I doubt there would be a measurable difference in concentration over one hour.