Question

A chemist has one solution containing 50% acid and a second one containing 25% acid. How much of each should be used to make 10 litres of a 40% acid solution?

Answer 1

Let x litres and y litres be the amount of acids from 50% and 25% acid solutions respectively.
As per the question
50% of x + 25% of y = 40% of 10

⇒ 0.50x + 0.25y = 4
⇒ 2x + y = 16 ………(i)
Since, the total volume is 10 liters, so
x + y = 10
Subtracting (ii) from (i), we get
x = 6
Now, putting x = 6 in (ii), we have
6 + y = 10 ⇒ y = 4
Hence, volume of 50% acid solution = 6litres and volume of 25% acid solution = 4litres.