What volume of a 2.5 M stock solution of acetic acid (HCHÀO) is required to prepare 100.0 milliliters of a 0.50 M acetic acid solution?

To prepare a 0.50 M acetic acid solution, you would need to dilute the 2.5 M stock solution. By using the formula M1V1 = M2V2, you can calculate the volume of the stock solution needed as: (0.5 M)(100.0 mL) = (2.5 M)(V2), where V2 is the volume of the stock solution needed. So, V2 = (0.5 M x 100.0 mL) / 2.5 M = 20.0 mL. Therefore, you would need 20.0 mL of the 2.5 M stock solution to prepare the desired 100.0 mL of 0.50 M acetic acid solution.