This is an example of dilution. To solve this problem, we must remember that:
number of moles of solute before dilution = number of moles of solute after dilution
moles is equivalent to the product of Volume and Molarity, therefore:
Mi Vi = Mf Vf
8.25 M * 25 mL = 2.40 M * Vf
Vf = 85.9375 mL
The final volume of solution is about 86 mL.
