you ask your lab assistant to prepare IL of solution Zeta at a concentration of 1M. He comes up to you with a 0.5M stock solution ans asks for help in calculating how much to use. what do you tell him?

Question

I dont think my answer is correct. I got 2000 mL of stock solution.
this is how i got my answer.

1) find N-fold: Stock concentration/working concentration = 0.5 M/1M = 0.5, so the n-fold is 0.5.

2) find stock volume: final volume of working solution/ n-fold = 1000mL/0.5n-fold= 2000mL of stock volume.

this answer doesnt make sense though because the final working solution volume should be 1L. can someone help me and tell me what im doing wrong :(

Answer 1

the stock solution is half the concentration of the desired solution

new (more concentrated) solution will have to be made

your calculation shows how to get the one mole of solute that would be in 1L of 1M solution
... the problem is the volume of solution needed at the lower concentration

Answer 2

1M / 0.5M = 2 n-fold dilution
1L = 1000 mL
1000mL / 2 = 500
Use 500 mL volume of stock + 500 mL of water