The reactant which reacts completely in the reaction is called limiting reactant or limiting reagent. The reactant which is not consumed completely in the reaction is called excess reactant . Question : 3 g of H2 react with 29 g of O2 to form H20.Which is the limiting reagent ? Answer: Thus O2 is present in excess.Hence H2 is the limiting reagent. … [Read more...] about Limiting Reagent