There is an "easy" way to do this if you are drinking somewhere that uses fluid ounces instead of mL. I call it the "divide by 60" method.
A US "standard drink" is 12 fl oz of 5%. Multiplying 12 * 0.05 gives us 0.6 fl oz of alcohol as a "standard drink". However, since we are going to be using % alcohol over and over, I find it easiest to not do the ...
The question provided a link to "How to determine the alcohol content of a mixed-drink?", so I'll assume you want a simpler, easier to understand answer.
Consider some common drinks:
12 US fl.oz. (355 mL) bottle of 5% beer = 355×5/100 = 17.75 mL alcohol.
1½ US fl.oz (44.4 mL) shot of 40% bourbon = 44.4×40/100 = 17.76 mL alcohol.
5 US fl.oz (148 mL) glass ...
It is easier to define the standard drink by volume as you won't have to switch between concentrations by volume (as is normal in most drinks) and grams.
This is probably where your recollection of moles comes in as somewhere in this morass of units they get involved.
14 grams of alcohol is 17.7 ml
so 30% alcohol (many spirits) to get to a 100% you need ...