Question

A laboratory technician needs to make a 36​-liter batch of a 40​% acid solution. How can the laboratory technician combine a batch of an acid solution that is pure acid with another that is ​20% to get the desired​ concentration?

Answer 1

9 Litre of 100% acid, 27 Litre of 20% acid solution

Explanation:

We know that 1 = 100% while

0.2 = 20%

We assume that x is volume of 100% solution, while y is volume of 20% solution.

x + 0.2y = (36×40/100)

x+0.2y= 14.4--------eqn(1)

x+y=36-------eqn(2)

x=36-y------eqn(3)

Input eqn(2) into 1 we have

(36-y)+0.2y= 14.4

-y+0.2y=14.4-36

-0.8y= 21.6

y=21.6/0.8

y=27

Hence, 27 Litre of 20% acid is required

From eqn(3) we can find value of x

x = 36-27

9 Litre of 100% acid is required

9 Litre of 100% acid, 27 Litre of 20% acid

Hence, the laboratory technician can combine a batch of 9 Litre of 100% acid, 27 Litre of 20% acid an acid solution that is pure acid with another that is ​20% to get the desired​ concentration