Do all components of beer evaporate at the same rate?

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Al Cole

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Al Cole  asked the Naked Scientists:
I you could measure the exact alcohol content of a pint of beer, then leave it until 50% had evaporated, would the remaining half pint contain the same concentration of alcohol and would the same volume of liquid evaporate compared to a control pint of 100% water?

I know water and alcohol have a strange affinity for each other, meaning you cannot fully distil alcohol to 100% purity.  I cannot work out if more alcohol would evaporate due to its increased volatility, or if this same property would cause water to evaporate at an increased rate along with the alcohol.

May seem like a small issue but without a definite answer I can`t seem to relax with my beer after a hard day's work.

Hope you can help


Alex Cole, London

What do you think?
« Last Edit: 23/10/2010 09:30:04 by _system »


Offline Atomic-S

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Do all components of beer evaporate at the same rate?
« Reply #1 on: 21/01/2011 06:25:49 »
I don't think that the relative proportions of alcohol and water would remain unchanged as the mix evaporated. Distillation works precisely because the constituents of the mixture do not evaporate at the same rate (with perhaps rare exceptions). This is a know fact of some mixtures, such as liquid air, in which evaporation causes the relative concentration of oxygen and nitrogen to change.