Description: In this phenomenon both magnesium metal and hydrochloric acid are limiting reactants. I have used this in a chemistry class, framing it as "The Case of the Mixed Up Masses". I tell them that I added varying amounts of magnesium metal but I forgot to label the flasks. If done correctly they should get the curve seen below. I learned about this on the NSTA Resource page.
Web Resource: NSTA Stoichiometry Balloon Race