An experiment requires 12.0 mL of a 0.100 M solution of HCl. If you have a 12.0 M HCl stock solution in the laboratory, how would you prepare enough 0.1 M solution to run at least 3 experiments?

Answer 1

Determine volume of HCl needed for the 3 experiments:

12.0 ml / experiment x 3 experiments = 36.0 mls needed

Use V1M1 = V1M2 to determine how much 12.0 M HCl stock you need to use to make enough:

V1 = initial volume = ?

M1 = initial molarity = 12.0 M

V2 = final volume = 36.0 ml

M2 = final molarity = 0.1 M

(x ml)(12.0 M) = (36.0 ml)(0.1 M)

x = 0.30 mls of 12.0 M HCl would be needed to make 36.0 mls of 0.1 M

(NOTE: in practice you'd want to make excess, e.g. make 40 mls instead of 36 mls)