Limiting Reagent: Definition & Examples

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What is limiting reagent

 

[Borek]

Limiting reagent.

 

[quicknote]

A limiting reagent is a substance involved in a chemical reaction that is completely used up, thus limiting the amount of product that can be formed. It determines the theoretical yield of a reaction and is usually the reactant present in the smallest amount.

For example, in the reaction between hydrogen gas (H2) and oxygen gas (O2) to form water (H2O), if there is 10 moles of H2 and 5 moles of O2, the O2 is the limiting reagent because it will be completely consumed before all the H2 is used up. This means that only 5 moles of water can be produced, even though there is excess H2 remaining.

Identifying the limiting reagent is important in determining the efficiency of a reaction and can also help in planning for the appropriate amounts of reactants needed to produce a desired amount of product. It is a fundamental concept in stoichiometry, the study of the quantitative relationships between reactants and products in a chemical reaction.

As a scientist, understanding the concept of limiting reagents is crucial in designing and conducting experiments, as well as in industrial processes where the efficiency and yield of reactions are important factors. By identifying and optimizing the limiting reagent, scientists can maximize the production of desired products and minimize waste.