Here's how to calculate the moles of copper sulfate needed:

1. Understand Molarity

* Molarity (M) is a unit of concentration that tells you the number of moles of solute dissolved in one liter of solution.

2. Use the Formula

* Molarity (M) = moles of solute / liters of solution

3. Rearrange the Formula

* moles of solute = Molarity (M) * liters of solution

4. Plug in the Values

* moles of copper sulfate = 0.125 M * 2.50 L

5. Calculate

* moles of copper sulfate = 0.3125 moles

Therefore, you need 0.3125 moles of copper sulfate to make 2.50 liters of a 0.125 M solution.