We wish to obtain a 40% solution of nitric acid by mixing a 20% solution in a 70% solution of acid. What percentage of the final solution should be taken from the 20% and 70% solutions?Solution:

Solution 1

Solution 2

Mixture

Nitric Acid

20%

70%

40%

Others

80%

30%

60%

x

y

F

\(x+y=F\)

\(y = F-x\)

\(0.2x+ 0.7y = 0.4 F\)

\(0.2x+ 0.7(F-x) = 0.4 F\)

\(0.2x +0.7F-0.7x = 0.4F\)

\(0.5 x = 0.3F\)

\(x = 0.6F\)

\(y = 0.4F\)

60% should be taken from the 20% solution and 40% from the other solution.