How many liters of each solution must be mixed to obtain 150 liters of a 36% solution?

Question

A chemist has two solutions of H2SO4. One has a 40% concentration and the other has a 25% concentration. Assume the chemist mixes some amount of the 40% with some amount of the 25% to obtain 150 liters of a 36% solution. How many liters of each solution must be mixed to obtain 150 liters of a 36% solution?

 

How do I solve this problem?

Answer 1

Lydia,

This is really just math, no chemistry involved. You need two equations.

 

If x is the amount of 40% solution

and y is the amount of 25% solution

then we get these two equations:

 

x + y = 150          and            .4x + .25y = .36(150)     solve left equation for x:

x = 150 - y        substitute into right equation:  .4(150 - y) + .25y = 54

Now solve for y:  60 - .4y + .25y = 54

                          -.15y = -6

                                y = 40 L of 25% solution

x = 150 - y = 150 - 40 = 110 L of 40% solution