please help me

Question

hydrochloric acid (HCl) is a corrosive acid. When ordered from a chemical supply company, its molarity is 12.0 M. How much of the stock solution of HCl needs to be used to make 1000 mL of a 3.0 M solution?

Answer 1

For this, you can use V1M1 = V2M2 where V1 and V2 are initial and final volumes, and M1 and M2 are initial and final molarities.  Thus,

   (x ml)(12.0 M) = (1000 ml)(3.0 M)

   x = 250 mls

So, you would use 250 ml of the stock 12.0 M and dilute it to a FINAL volume of 1000 mls to make 3.0 M.