I was just talking to a friend about how 1 part water plus 1 part ethanol becomes 1.92 parts solution.

This raised a question for me that I have yet to research/answer. Maybe one of you knows... if the above solution is 50% ABV, what happens if I add one more part alcohol to the solution? Is it now 66.6% ABV? More? Less? How does ABV take into account the fact that this solution is packed together tighter than its constituent parts?

The wikipedia article has all the charts and formulas you need. https://en.wikipedia.org/wiki/Alcohol_by_volume

(To make the above solution 50% abv, btw, you need to keep adding water until it's 2 (liters, whatever) total volume.)

This is a common issue for people doing liquors at home: you mix 1l of alcohol which you used to extract some flavour with 1l of water and don't get back 2l.

Thank you for being the best of HN.

The muderation might be awful, but the users are sharp.

Learned something new, and I'm a chem grad.