Limiting & Excess Reactants

Front

What is a limiting reactant?

Back

The limiting reactant is the substance that is completely consumed in a chemical reaction, determining the maximum 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 1A + 2B -> 3C, if you have 4 moles of A and 7 moles of B, which is the limiting reactant?

Back

B is the limiting reactant because you need 2 moles of B for every mole of A, and you can only use 4 moles of A with 8 moles of B.

Front

What happens to the excess reactant after the reaction?

Back

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

Front

If 10 grams of reactant A reacts with 20 grams of reactant B, how do you determine which is limiting?

Back

Convert the grams of each reactant to moles, then use the balanced equation to find out which reactant will run out first.

Front

What is the significance of identifying limiting and excess reactants?

Back

Identifying limiting and excess reactants helps in calculating the yield of products and understanding the efficiency of a reaction.

Front

In a reaction, if 5 moles of A produce 10 moles of B, how many moles of A are needed to produce 20 moles of B?

Back

10 moles of A are needed to produce 20 moles of B.

Front

What is the formula to calculate the theoretical yield of a product?

Back

The theoretical yield can be calculated using the moles of the limiting reactant and the stoichiometry of the balanced equation.

Front

If 3 moles of A react with 2 moles of B, what is the mole ratio of A to B?

Back

The mole ratio of A to B is 3:2.