I lost the cap to my bottle of scotch, will all the alcohol evaporate?!
Answers:
No but the flavor will. Plastic wrap over the neck solves it.
Or drinking it in one gulp :)
It certainly will, eventually. As another answerer said, tin foil should keep it safe for awhile. But you should work on that bottle first, until moving on to something else.
Shove a ball of aluminium foil into it