Answer:
To prepare a 0.5M 500cm^3 solution of MgSO4 from a 2.5M stock solution of MgSO4, you can use the following formula:
C1V1 = C2V2
where C1 is the concentration of the stock solution, V1 is the volume of the stock solution needed, C2 is the desired concentration of the final solution, and V2 is the final volume of the solution.
Rearranging the formula, we get:
V1 = (C2 x V2)/C1
Substituting the values we have:
V1 = (0.5 x 0.5)/2.5 = 0.1 L = 100 mL
This means we need 100 mL of the stock solution to prepare the final solution. To prepare the final solution, we can use a volumetric flask and add 100 mL of the stock solution to it. We can then add distilled water to the flask until the volume reaches 500 mL, giving us a 0.5M 500cm^3 solution of MgSO4.