1. The problem statement, all variables and given/known data What volume of water must be added to a sample of 8.00 M Nitric Acid in order to produce 500. mL of 1.25 M Nitric Acid? (A) 422 mL (B) 499 mL (C) 625 mL (D) 0.625 L (E) None of The Above The correct answer is A in bold. 2. Relevant equations molarity= moles/Liter 3. The attempt at a solution This is problem 1 from: http://www.adriandingleschemistrypages.com/apquiz04D.html .5 L(500. mL ) x 1.25 moles HNO3/Liter solution=0.625 moles HNO3 (0.625/.5)=8/(1+x) The reason I left it as 1+x is b/c I assumed the volume of the solution is already 1 Liter and therefore x represents the amount of water that needs to be added in order to reduce the concentration to (.625/.5) The answer I am left with is x=5.4, which is not one of the choices. I think that maybe I should not have assumed a volume of 1 L, but that the problem should say what the original volume is.......But maybe not. I'm not sure what I did wrong.