Question

It is required to prepare 1250kg of a solution composed of 12 wt. % ethanol and 88 wt. % water. Two solutions are available, the first contains 5 wt. % ethanol, and the second contains 25 wt. % ethanol. How much of each solution are mixed to prepare the desired solution? Check your answer

Answer 1

1.Ethanol balance

$A(5/100)+B(25/100)=M(12/100)$

$0.05A+0.25B=0.12M$

$A=(150-0.25B)/0.05=3000-5B$

2.Water balance

$0.95A+0.75B=0.88M=0.88*1250=1100$

$0.95A+0.75B=1100$

Sub.(1) in (2)

$0.95(300-5B)+0.75B=1100$

$2850-4.75+0.75B=1100$

$4B=1750$

$B=437.5kg$

Sub B in (1):

$A=3000-5*437.5=812.5kg$

Answer:812.5kg 5% and 437.5kg 25% ethanol