Question

What vol fo stock soln would you use to prepare 150 mL of a 24 mg/L Cu standard soln if the Cu stock soln had a concentration of 200 mg/L?

* Please do not provide answer. I really need to figure out how to solve this problem so general formulas and some guidance would be much appreciated.. *

Answer 1

initial concentration is given that stock solution concentration C1 = 200 mg / L

stock solution volume needed = V1

after dilution concentration = C2 = 24 mg/L

this diluted solution volume = V2 = 150 mL

formula in dilution : C1 V1 = C2 V2

200 x V1 = 24 x 150

V1 = 18 mL

stock solution volume = 18 mL

extra explation :

volume of water added = V2 -V1 = 150 -18 = 132 mL
take 18 mL stock solution add 132 mL water , you get total 150 mL (18 + 132 ) with concentration 24 mg /L

i think you got this . good luck dear