Definition of Limiting Reagent

The reactant in a chemical reaction that gets consumed wholly or used up first, and thus, stops the reaction from proceeding further, and limits the amount of product formed is called limiting reactant of that particular reaction.

The reaction is stopped when the limiting reactant is consumed wholly, even if the other reactants are present in excess. Also, the quantity of limiting reactant limits the amount of product formed, so it becomes quite important to study about limiting reactant of any chemical reaction. By determining the limiting reactant, we can optimize the yield of the reaction accordingly. 

The concept of limiting reactant can be learnt with the help of the image discussed below,

A chemical reaction occurs when one or more reactants undergo some chemical changes to form new products. If the reaction involves two or more reactants, one of the reactants becomes the limiting reactant, when the reaction occurs practically. As, theoretically, a chemical reaction occurs in a stoichiometric proportion of the number of moles of reactants and products, but when a chemical reaction is carried out practically, it is impossible to have exact proportions of reactant moles due to limitations in the measuring instruments. Thus, the reactant which gets exhausted first and stops the reaction from proceeding further is termed a limiting reagent. 

In this article, we will explore the definition, examples, formula, and some examples of limiting reactants.