You have a piece of Mg of an unknown mass, and a beaker of water in which is dissolved an unknown amount of HCl. Design an experiment to determine which reactant is the limiting reactant. I'm not too sure how to get started with this problem. I was thinking you could place the magnesium into the beaker of H20 and HCl and see if the magnesium dissolves at all. If all of it dissolves than the Magnesium would be the limiting reactant... but if not all of it dissolved HCl would be the limiting reactant - Can anyone tell me if I am on the right track?