Limiting & Excess Reactants

Front

What is a limiting reactant?

Back

The limiting reactant is the substance that is completely consumed in a chemical reaction, limiting the amount of product that can be formed.

Front

What is an excess reactant?

Back

The excess reactant is the substance that remains after a chemical reaction has occurred, as it is not completely consumed.

Front

How do you identify the limiting reactant in a reaction?

Back

To identify the limiting reactant, compare the mole ratio of the reactants used in the reaction to the mole ratio required by the balanced equation.

Front

In the reaction 2H₂ + O₂ → 2H₂O, which is the limiting reactant if you have 3 moles of H₂ and 1 mole of O₂?

Back

H₂ is the limiting reactant because you need 2 moles of H₂ for every mole of O₂, and you only have enough H₂ for 1.5 moles of O₂.

Front

What happens to the excess reactant after the reaction?

Back

The excess reactant remains unreacted and can be measured after the reaction is complete.

Front

If you have 10 pieces of bread, 4 tablespoons of peanut butter, and 20 tablespoons of jelly, what is the limiting reactant for making sandwiches?

Back

Peanut butter is the limiting reactant because you need 1 tablespoon of peanut butter for each sandwich.

Front

In a reaction, if 5 moles of A react with 3 moles of B to produce 2 moles of C, what is the mole ratio of A to B?

Back

The mole ratio of A to B is 5:3.

Front

If you can make 13 grilled cheeses with 26 slices of bread and 14 pieces of cheese, what is the limiting reactant?

Back

Bread is the limiting reactant because you need 2 slices of bread for each grilled cheese.

Front

What is the significance of the limiting reactant in a chemical reaction?

Back

The limiting reactant determines the maximum amount of product that can be formed in a chemical reaction.

Front

How do you calculate the amount of product formed from a limiting reactant?

Back

Use the mole ratio from the balanced equation to convert moles of the limiting reactant to moles of the product.