Question

A chemistry teacher needs to make 10 L of 36% sulphuric acid solution. The acid solutions available are 30% sulphuric acid and 50% sulphuric acid, by volume. How many litres of each solution must be mixed to make the 36% solution?

Answer 1

7 L of 30% acid

3 L of 50% acid

Explanation:

If x is the volume of 30% acid, and y is the volume of 50% acid, then:

x + y = 10

0.30 x + 0.50 y = 0.36 (10)

Solve the system of equations using substitution.

0.30 (10 − y) + 0.50 y = 3.6

3 − 0.30 y + 0.50 y = 3.6

0.20 y = 0.6

y = 3

x = 7

The chemistry teacher needs 7L of 30% acid and 3L of 50% acid.