How much pure acid must be added to 2 liters of a 10% solution of acid to obtain a mixture that is 20% acid?

Answer 1

amount of pure acid added ---- x litres

.1(2) + x = .2(x+2)
2 + 10x = 2(x+2)
2+10x = 2x + 4
8x = 2
x = 1/4 L