To make 5.0 L of a fruit punch that contains 10% v/v ethanol, how much 95% v/v ethanol must be mixed with how much fruit juice?

Answer 1

5(.10) = x(.95) + (5-x)(.00)

.5 = .95x

x= .5/.95 = 10/19 = about 0.526 L of 95% ethanol mixed with 5-.526 = 4.474 L of fruit juice

yields 5 L of 10% fruit punch

.526(.95) + 4.74(.00) = .50 + 0 = .50 = 5(.10)

.95 is within .85 of .10

0 is within .10 of .10

so you need much more fruit juice than ethanol

you need a ratio of .10/.85 = .118 = .526/4.474= .118