Question

A chemist has one solu6on that is 40% sulfuric acid and one that is 10% sulfuric acid. How much of each should she use to make 20 liters of a solu6on that is 28% sulfuric acid?

Answer 1

12 L of 40% sulfuric acid solution and 8 L of 10% sulfuric acid solution are needed to make 20 L of sulfuric acid solution.

Step-by-step explanation:

For first solution of sulfuric acid :

C₁ = 40% , V₁ = ?

For second solution of sulfuric acid :

C₂ = 10% , V₂ = ?

For the resultant solution of sulfuric acid:

C₃ = 28% , V₃ = 20L

Also,

V₁ + V₂ = V₃ = 20L ......................................(1)

Using

C₁V₁ + C₂V₂ = C₃V₃

40×V₁ + 10×V₂ = 28×20

So,

40V₁ + 10V₂ = 560........................................(2)

Solving 1 and 2 as:

V₂ = 20 - V₁

Applying in 2

40V₁ + 10(20 - V₁) = 560

40V₁ + 200 - 10V₁ = 560

30V₁ = 360

V₁ = 12 L

So,

V₂ = 20 - V₁ = 8L

12 L of 40% sulfuric acid solution and 8 L of 10% sulfuric acid solution are needed to make 20 L of sulfuric acid solution.