Limiting and Excess Reactants in Reactions

In this video, Mr. Post explains how to determine limiting and excess reactants in stoichiometry problems using analogies and problem-solving examples. He starts with a hot dog analogy to introduce the concept, then applies it to chemical reactions involving magnesium and oxygen, and calcium and oxygen. The video demonstrates how to identify which reactant limits the product formation and which is in excess, using dimensional analysis and mole ratios.

In the barbecue analogy, what determines the maximum number of hot dogs you can make?

• The number of buns available

• The number of hot dogs available

• The size of the grill

• The number of guests

What is the limiting reactant in a chemical reaction?

• The reactant that is left over

• The reactant that is used up first

• The reactant that is most abundant

• The reactant that is least expensive

In the magnesium and oxygen reaction, what is the maximum amount of magnesium oxide that can be produced?

• 72 grams

• 40 grams

• 15.5 grams

• 25.7 grams

Which reactant is the excess reactant in the magnesium and oxygen problem?

• Oxygen

• None of the above

• Magnesium

• Magnesium oxide

In the calcium and oxygen reaction, what is the limiting reactant?

• Calcium

• Both calcium and oxygen

• Oxygen

• Calcium oxide

How much calcium oxide can be produced when all the calcium is used up in the reaction?

• 49.1 grams

• 37.1 grams

• 56 grams

• 130 grams

What is the role of dimensional analysis in these problems?

• To convert units and calculate product amounts

• To determine the color of the product

• To balance the chemical equation

• To measure the temperature

What happens when the limiting reactant is completely used up?

• The reaction stops

• The excess reactant is used up

• The product is destroyed

• The reaction continues

Why is it important to identify the limiting reactant in a reaction?

• To determine the maximum amount of product

• To increase the reaction speed

• To change the color of the product

• To reduce the cost of reactants

What is the excess reactant in the calcium and oxygen reaction?

• Oxygen

• Calcium

• None of the above

• Calcium oxide