How many milliliters of a 15% acid solution and how many milliliters of a 3% acid solution must be mixed to get a 45ml of a 7% acid solution?

Question

How many milliliters of a 15% acid solution and how many milliliters of a 3% acid solution must be mixed to get a 45ml of a 7% acid solution?

Answer 1

Hi Jennifer:

 

If we use x ml of 15% solution,

we use (45-x)ml of 3% solution

 

Acid concentrations:

.15x + .03(45-x) = .07(45)

multiply through by 100 to clear decimals

15x + 3(45-x) = 7(45)

15x + 135 - 3x = 315

12x = 180

x = 12 ml of 15% solution

 

45-12 = 33 ml of 3 % solution