Limiting Reagent

Definition

The limiting reagent in a chemical reaction is the reactant that gets completely used up first and thus limits how much product can be formed.

Analogy

Think about baking cookies. If your recipe calls for 2 eggs and 3 cups of flour to make 12 cookies but you only have 1 egg, then no matter how much flour you have, you can only make half batch or 6 cookies. Here, eggs are your limiting reagent.

Related terms

Excess Reagent: This is any reactant that remains after a chemical reaction has reached completion. In our cookie analogy, this would be any extra flour left over after all eggs have been used up.

Stoichiometry: This branch of chemistry deals with quantitative relationships between reactants and products in a chemical reaction - like figuring out which ingredient will run out first when baking cookies!

Yield: Yield refers to how much product was actually produced when carrying out a reaction.