Limiting Reagent/Reactant

Ms. Knick HAHS

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Reacting Amounts

In a table setting, there is 1plate, 1 fork, 1 knife, and 1 spoon.

How many table settings arepossible from 5 plates, 6 forks,4 spoons, and 7 knives?

What is the limiting item?

What happens in a chemical reaction, if there is an insufficient amount of one reactant?

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Limiting Reagent: the reagent that is completely used up in a chemical reaction.

Excess Reagent: reagent not completely used up in a chemical reaction.

Example:Find the limiting reagent when 1.22g O2 reacts with 1.05g H2 to produce H2O. How many grams of water will be produced?

Method

Use the moles of each of the reactant to calculate the product of interest.

The reactant that yields the smaller calculated value of product is the limiting reagent.

This calculated amount is also known as the theoretical yield.

Example: Find the limiting reagent when 1.22g O2 reacts with 1.05g H2 to produce H2O. How many grams of water will be produced?

Calculate H2O moles produced by using each of the reactants.

The actual amount H2O produced is the smaller one of the two values.

Use the smaller mole value to convert to grams.

This is the theoretical yield.