# A solution contains 25% copper sulphate. Another solution contains 50% copper sulphate. How much of each solution should be used to make 1000 mL of a solution that's 45% copper sulphate?

##### 1 Answer

You need **600 mL** of 25% solution and **600 mL** of 50% solution.

#### Explanation:

You need to use the information given to you to write two equations, one that focuses on the mass of the individual solutions that you mix, and the other that focuses on how much copper sulfate the target solution must contain.

Let's say that **1000 mL**, so you can write

Now, the target solution is known to **45%** copper sulfate. This means that the amount of copper sulfate you get in **1000 mL** is equal to

The amount of copper sulfate you get from each solution must amount to **450 g**. This means that you can write

The two equations are

Use the first equation to write

This means that

Therefore, if you mix **600 mL** of 25% solution with **400 mL** of 50% solution you get a solution that is **45%** copper sulfate.