A student is asked to prepare 250.0 mL of 3.5 M copper (II) sulfate from solid copper (II) sulfate pentahydrate. Describe how this solution should be made in the chemistry laboratory.

I'm not quite sure if you want 3.5M CuSO4 or 3.5M CuSO4.5H2O. I am assuming the former and want to start with CuSO4.5H2O.

How many mols CuSO4 do you want? That's M x L = 3.5 x 0.250 = about 0.9 but you need to do that more accurately.
Since there is 1 mol CuSO4 in 1 mol CuSO4.5H2O, you need the same 0.9 mol CuSO4.5H2O.
g CuSO4.5H2O = mol CuSO4.5H2O x molar mass CuSO4.5H2O

To prepare a 3.5 M solution of copper (II) sulfate from solid copper (II) sulfate pentahydrate, the student should follow these steps in the chemistry laboratory:

1. Determine the amount of solid copper (II) sulfate pentahydrate needed:
- The molar mass of copper (II) sulfate pentahydrate, CuSO4·5H2O, can be calculated by adding the molar masses of its individual components:
- Copper (Cu): 63.55 g/mol
- Sulfur (S): 32.07 g/mol
- Oxygen (O): 16.00 g/mol (4 atoms in sulfate)
- Hydrogen (H): 1.01 g/mol (10 atoms in pentahydrate)
- Therefore, the molar mass of copper (II) sulfate pentahydrate is:
- (63.55 + 32.07 + (16.00 * 4) + (1.01 * 10)) g/mol = 249.69 g/mol

2. Calculate the mass of copper (II) sulfate pentahydrate needed:
- As the desired solution is 250.0 mL and has a concentration of 3.5 M, the student needs to find the number of moles of copper (II) sulfate in the solution.
- Moles = concentration (M) × volume (L)
- Volume (L) = 250.0 mL ÷ 1000 = 0.2500 L
- Moles = 3.5 M × 0.2500 L = 0.875 moles
- Mass (g) = Moles × molar mass (g/mol)
- Mass (g) = 0.875 moles × 249.69 g/mol = 218.29 g

3. Dissolve the solid copper (II) sulfate pentahydrate in water:
- Measure out the calculated mass of copper (II) sulfate pentahydrate, 218.29 g, using a balance.
- Pour the solid into a suitable container, such as a beaker.
- Add about half of the required volume of distilled water (125 mL) to the beaker.
- Stir the mixture thoroughly until all of the solid has dissolved.

4. Dilute the solution to the desired final volume:
- Transfer the dissolved copper (II) sulfate solution from the beaker to a volumetric flask using a funnel.
- Rinse the beaker with distilled water several times to make sure all the dissolved copper (II) sulfate is transferred.
- Add distilled water to the volumetric flask gradually, while swirling, until the bottom of the meniscus aligns with the graduation mark on the flask.
- Cap the flask and invert it several times to ensure thorough mixing.

The resulting solution should be a 250.0 mL, 3.5 M copper (II) sulfate solution prepared from solid copper (II) sulfate pentahydrate.