How to solve this?

Question

You have been provided with 250 ml of a stock solution of 5 M Sodium acetate. Explain how you would prepare 100 ml of 0.5 M Sodium acetate working solution from the given stock.

Answer 1

To go from 5 M to 0.5 M requires a 10 fold dilution (5/10 = 0.5). That means 1 ml diluted to 10 mls, or 2 mls diluted to 20 mls, etc. Thus, to make 100 mls, you would take 10 mls of the original stock and dilute it to a final volume of 100 mls.

Done another way:

V1M1 = V2M2

(x ml)(5 M) = (100 ml)(0.5 M)

x ml = (100 ml)(0.5 M)/5 M

x = 10 mls