Question 625529
how much water must be evaporated from 240 pounds of a solution that is 3% alcohol to strengthen it to a solution  that is 5% alcohol?
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3% of 240 pounds = 7.2 pounds of alcohol
If 7.2 pounds = 5%, the total = 7.2/0.05 = 144 pounds
240 - 144 = 96 pounds of water to evaporate.
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PS  That won't work, the alcohol has a lower boiling so it will evaporate first.
If it did work, a lot of people would make stronger booze that way.