What is a limiting reactant in a chemical reaction?

A limiting reactant is defined as the substance that is completely consumed first during a chemical reaction. This concept is crucial in stoichiometry, as it determines the maximum amount of product that can be formed. When one reactant is used up, the reaction cannot proceed further, even if other reactants are still available. Consequently, the limiting reactant sets the limit on the amount of product produced in the reaction.

In practical terms, this means that if you have a reaction where one reactant is in lower quantity compared to the others, that reactant will be the limiting factor. For instance, if a recipe requires certain amounts of various ingredients, the ingredient you run out of first will dictate how many servings you can make, similar to how the limiting reactant functions in a chemical equation.

The other options refer to concepts that do not accurately capture the definition of a limiting reactant. While they discuss different aspects of a chemical reaction, they do not clarify the role of a limiting reactant as the substance that restricts the amount of product made by being consumed entirely.