Limiting reagent

Equal masses of iron (Fe) and sulfur (S) react to form iron sulfide (FeS), but because of its higher atomic weight, iron is the limiting reagent and once all the iron is consumed some sulfur remains unreacted

The limiting reagent (or limiting reactant or limiting agent) in a chemical reaction is a reactant that is totally consumed when the chemical reaction is completed.[1][2] The amount of product formed is limited by this reagent, since the reaction cannot continue without it. If one or more other reagents are present in excess of the quantities required to react with the limiting reagent, they are described as excess reagents or excess reactants (sometimes abbreviated as "xs"), or to be in abundance.[3]

The limiting reagent must be identified in order to calculate the percentage yield of a reaction since the theoretical yield is defined as the amount of product obtained when the limiting reagent reacts completely. Given the balanced chemical equation, which describes the reaction, there are several equivalent ways to identify the limiting reagent and evaluate the excess quantities of other reagents.

  1. ^ Olmsted, John; Williams, Gregory M. (1997). Chemistry: The Molecular Science. Jones & Bartlett Learning. p. 163. ISBN 0815184506.
  2. ^ Zumdahl, Steven S. (2006). Chemical Principles (4th ed.). New York: Houghton Mifflin Company. ISBN 0-618-37206-7.
  3. ^ Masterton, William L.; Hurley, Cecile N. (2008). Chemistry: Principles and Reactions (6 ed.). Cengage Learning. ISBN 978-0-495-12671-3.