24.5 ml of water are added to a 1.20 molar solution of nitric acid. If the concentration decreases to 0.55 molar, what volume of the concentrated solution was used?
1.20 M x mL = (24.5 mL + mL) x 0.55 M
Solve for mL.
Check my thinking. When you finish the calculation, check it my equating mL x 1.2M should equal volume of new solution x 0.55M.