100 likes | 189 Views
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.
E N D
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 ReactantHow many sandwiches can be made?
Analogy for Limiting ReactantsPizza 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
Answer the following questions: • 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