To what volume should you dilute 43.5mL of a 4.20M KI solution so that 24.0mL of the diluted solution contains 2.80g of KI? Please if you can explain it to me I am so confused.

Answer 1

How many mols KI do you want? That's mols KI = grams KI/molar mass KI.
2.80/about 166 = about 0.0169 mols KI.
You want that to be contained in 24.0 mL; that's the equivalent of 0.0169/0.024L = about 0.703 M

So 4.2 M soln is to be diluted so that it will be 0.0703 M

4.2M x 43.5 mL/X mL = 0.703 M
x mL = about 260 mL.

Let's check it to see if that works.
Dilute 43.5 mL of 4.2M KI to 260 mL.\
4.2 x (43.5 mL/260 mL) = 0.703M
If we take 24.0 mL of that solution, how many mols will it be?
That will be M x L = 0.703 x 0.024 = 0.0169 mols KI. How many g is that? That's g = mols x molar mass = 0.0169 mols x 166 g/mol = 2.80 g KI which is what we wanted.

Answer 2

thank you so very much