Limiting and Excess Reactants Quiz

What is a limiting reactant in a chemical reaction?

• A reactant that speeds up the reaction.

• A reactant that does not participate in the reaction.

• A reactant that is left over after the reaction.

• A reactant that is used up first, limiting the amount of product formed.

In the visual example with A and B, what happens when A is completely used up?

• The reaction continues with B forming more products.

• The reaction stops because there is no more A to react.

• A and B both become excess reactants.

• The reaction reverses and forms more reactants.

How does a bar graph help in understanding limiting and excess reactants?

• It calculates the exact amount of reactants needed.

• It predicts the final product of the reaction.

• It visually represents the quantities of reactants and products.

• It shows the speed of the reaction.

In the bar graph example, what indicates that the reaction has stopped?

• All products are formed.

• All reactants are used up.

• Reactant two is completely consumed.

• Reactant one is completely consumed.

In the ammonia and oxygen example, what is the first step to identify the limiting reactant?

• Choose any reactant and calculate how much of the other reactant is needed.

• Calculate the total mass of products.

• Measure the temperature change in the reaction.

• Determine the speed of the reaction.

What is the molar mass of oxygen used in the stoichiometry calculation?

• 14 grams per mole

• 18 grams per mole

• 32 grams per mole

• 16 grams per mole

How much of the excess reactant is left over in the ammonia and oxygen example?

• 2.00 grams

• 4.00 grams

• 1.70 grams

• 0.30 grams

Why is it important to use the limiting reactant to calculate the amount of product formed?

• Because it is always present in excess.

• Because it is the most expensive reactant.

• Because it speeds up the reaction.

• Because it determines the maximum amount of product that can be formed.

In the final example, how much water is produced from the limiting reactant?

• 1.70 grams

• 2.70 grams

• 3.00 grams

• 4.00 grams

What is a cost-efficient way to set up a chemical reaction according to the video?

• Increasing the temperature of the reaction.

• Calculating the exact amounts of reactants to avoid excess.

• Using more reactants than needed.

• Using only one reactant.