As a research assistant, you are asked to prepare a 3.00 liter solution of magnesium sulfate at 45.0 micromoles per liter. How many moles of magnesium sulfate are required to make this solution?

From the question given, we obtained the following:

Molarity = 45.0 micromoles per liter = 45x10^-6mol/L

Volume = 3L

Mole = ?

Molarity = mole / Volume

Mole = Molarity x Volume

Mole = 45x10^-6 x 3

Mole = 1.35x10^-4 moles

Therefore, 1.35x10^-4 moles of magnesium sulfate is needed to make the solution.