# How much does a reaction really produce?

## Presentation on theme: "How much does a reaction really produce?"— Presentation transcript:

How much does a reaction really produce?
Limiting Reactants

Reactants combine in specific whole-number ratios
Limiting Reactant: reactant that is used up first limiting the amount of the other reactants that can participate in the reaction Excess Reactant: any reactant that is not completely used up in the chemical reaction

Determining Limiting Reactant How many sandwiches can be made?

Analogy for Limiting Reactants Pizza Time
Analogy for Limiting Reactants Pizza Time!! The following ingredients are required to make one pizza: 400 g flour 50 mL water 10 g yeast 120 g sauce 250 g cheese 5 g oregano 5 g basil

You are given the following supplies…
500 pizza pans 60 kg sauce 100 kg cheese 2.5 kg oregano 2.5 kg basil 5 kg yeast 25 L water 200 kg flour

Which ingredient is the limiting reactant? How many pizzas can be made? If you sold each pizza for \$3.50, how much money can be made from the sale of this many pizzas? If you were able to get twice as much cheese, how many pizzas would you be able to make?

Determining the Limiting Reactant for Reactions
Change all of the reactants to moles Select one of the reactants (Reactant #1) Use the mole ratio to determine how much of the other reactant (Reactant #2) would be needed to complete the reaction. Evaluate your answer to determine the limiting reactant

Evaluating the Results of the Previous Calculation
If the amount of reactant #2 necessary (determined from mole ratio) is less than the amount present, reactant #1 is the limiting reactant If the amount of reactant #2 necessary is greater than the amount present, reactant #2 is the limiting reactant

Determining the Limiting Reactant for Reactions
Change all of the reactants to moles Select one of the reactants (Reactant #1) Use the mole ratio to determine how much of the other reactant (Reactant #2) would be needed to complete the reaction. Evaluate your answer to determine the limiting reactant Perform calculations based on the limiting reactant

Why is determining the limiting reactant important?
Chemicals cost money If the most expensive chemical is the limiting reactant, money can be saved