What is a limiting reactant?

A limiting reactant is defined as the substance that is completely consumed in a chemical reaction, which, in turn, restricts the amount of product that can be formed. This concept is key in stoichiometry because it determines how far a reaction will proceed. When one reactant is limiting, it gets fully used up before the others, thus dictating the maximum yield of the product based on the amount of the limiting reactant available.

In a balanced chemical equation, the coefficients represent the ratios of the reactants and products. If one reactant is present in a lesser quantity than required by these ratios, it will limit production. Once the limiting reactant is depleted, the reaction cannot continue even if other reactants are still available.

Understanding the role of the limiting reactant is essential for accurately predicting how much product will be made in a reaction, which is crucial for practical applications in fields such as pharmaceuticals, materials science, and manufacturing.