Question

A laboratory technician needs to make a 40-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?

The laboratory technician can combine L of the pure acid solution with L

of the 20% acid solution to get the desired concentration

Answer 1

The technician can combine 10 liters of pure acid with 30 liters of 20% acid to get the desired concentration

Explanation:

For pure acid, the concentration will be 100%

Let the liters of pure be a and the liters of 20% be b

Since we want 40 liters of total;

a + b = 40 ••••••••(i)

Also,

100% of a + 20% of b = 40% of 40

a + 0.2b = 16 •••••(ii)

From ii , a = 16-0.2b

Put this into i

16-0.2b + b = 40

0.8b = 40-16

0.8b = 24

b = 24/0.8

b = 30

Since a + b = 40

a = 40 - b

a = 40-30

a = 10