Question

For a chemistry experiment, a student is given a solution that contains 20 ml of Chemical M and 60 ml water. The student needs to use it to prepare a solution that contains 10% of Chemical M. Which equation can be used to find the amount of water,w, in ml, that the student should add to the given solution to get the desired solution?

Answer 1

The Concentration-Volume equation is used to solve this problem.

Explanation:

If 20ml of chemical dissolves in 100ml of water it gives the 20 % of the solution, that's why C₁ and V₁ are 20 and 100 respectively.

The Percentage of a given solution is

C₁V₁ = C₂V₂

20 × 100 = C₂ × 60  

C₂ = 20 × 100\60

C₂ =  33.33 %

Now, how much amount of water is required to prepare the 10% of solution from 33.33% of the solution. Therefore,

C₁V₁ = C₂V₂

33.33 × 60 = 10 × V₂

V₂ = 33.33 × 60\10

V₂ = 199.98 ≅ 200 ml of water

200ml water should be added to the given solution to prepare the desired solution.