Question

Write a short note on limiting reagents.

Answer 1

Limiting Reagent

• In a chemical reaction, the limiting reagent is the reactant that is used first, limiting the amount of product that may be created.
• It is completely consumed after the completion of the reaction.
• If this reagent is completely consumed, then the reaction comes to an end.
• It is basically that reactant which yields the minimum amount of product.
• Let us consider the following reaction,

$\underset{\mathrm{Nitrogen}}{\underbrace{{\mathrm{N}}_2}}\left(\mathrm{g}\right)+\underset{\mathrm{Hydrogen}}{\underbrace{3{\mathrm{H}}_2}}\left(\mathrm{g}\right)\to \underset{\mathrm{Ammonia}}{2\underbrace{{\mathrm{NH}}_3}}\left(\mathrm{g}\right)$

• $3$ moles of Hydrogen gas $\left({\mathrm{H}}_2\right)$ must react with $1$ mole of Nitrogen gas $\left({\mathrm{N}}_2\right)$ to produce $2$ moles of Ammonia $\left({\mathrm{NH}}_3\right)$.
• But what if there are only $2$ moles of hydrogen gas and $1$ mole of nitrogen available throughout the reaction.
• In that circumstance, the total amount of nitrogen available cannot be utilized.
• As a result, hydrogen gas is dubbed the limiting reagent for this reaction since it limits the reaction.

Determination of Limiting Reagent

• Make sure the chemical equation is balanced.
• Calculate the total moles of all reactants throughout the reaction.
• Determine the total number of products generated throughout the reaction.
• Find the reactant that produces the least amount of products, which is known as a limiting agent.