Question

a lab technician needs to combine 30% alcohol solution with 35% alcohol solution to make 5l of 33% alcohol solution . how many luters of the 30% solutio and of the 35% solution will be used

Answer 1

To answer the problem, use the material and component balance. Let x and y be the volume of 30% and 35% solution, respectively. The balances are shown below,

Overall Material Balance:       x + y = 5
Component Balance:             0.30x + 0.35y = 5 x 0.33

Solving simultaneously for the values of the variables gives x = 2 and y = 3.

Thus, the technician needs 2L of 30% alcohol and 3L of 35% alcohol.