Calculating Balancing Numbers in Chemical Reactions and Limiting Reactants

The video tutorial explains the concept of relative formula mass and its application in chemical reactions. It uses two examples: the decomposition of hydrogen peroxide and the reaction of sodium with oxygen, to demonstrate how to calculate moles and balance chemical equations. The tutorial also introduces the concept of limiting reactants, explaining how to identify which reactant is completely used up in a reaction.

What is the purpose of using relative formula mass in chemical reactions?

• To measure the volume of a gas

• To calculate the number of moles

• To determine the color of a substance

• To find the temperature of a reaction

In the decomposition of hydrogen peroxide, what is the ratio of moles of hydrogen peroxide to oxygen to water?

• 2:2:1

• 1:1:1

• 2:1:2

• 1:2:1

How many moles of sodium react with oxygen to form sodium oxide in the given example?

• 2 moles

• 4 moles

• 3 moles

• 5 moles

What is the mass of oxygen that reacts with sodium in the example provided?

• 0.5 grams

• 0.7 grams

• 1.0 grams

• 1.5 grams

What is a limiting reactant in a chemical reaction?

• A reactant that is completely used up

• A reactant that is in excess

• A reactant that changes color

• A reactant that does not participate

In the reaction between calcium and hydrochloric acid, which reactant is the limiting reactant?

• Water

• Hydrochloric acid

• Calcium

• Oxygen

How many moles of calcium are involved in the reaction with hydrochloric acid?

• 0.10 moles

• 0.15 moles

• 0.25 moles

• 0.20 moles