posted by maggie .
How do you prepare a solution of 12 M HCl and want to prepare 500 mL of a 0.4 M solution. Assume you have a 500-mL volumetric flask
I don't think your question is worded properly. I think you have 12 M HCl and want to prepare 500 mL of 0.4M.
c1v1 = c2v2
12*mL = 0.4*500
Solve for mL of the 12 M material. Place that in the 500 mL volumetric flask and make to the mark. Shake thoroughly.