Chemical Reactions and Conservation of Mass

Mr. Sunberg introduces the concepts of combustion, corrosion, and the law of conservation of mass. Combustion is described as a highly exothermic reaction involving oxygen, often producing carbon dioxide and water vapor. Corrosion, particularly rust, is explained as the oxidation of metals in the presence of moisture. Methods to prevent corrosion, such as galvanization, are discussed. The law of conservation of mass is detailed, emphasizing the balance of mass in chemical reactions. Practical demonstrations of combustion and corrosion are provided to reinforce the concepts.

What is the primary requirement for a combustion reaction to occur?

• Presence of carbon dioxide

• Presence of nitrogen

• Presence of oxygen

• Presence of water

Which of the following is a product of the combustion of methane?

• Nitrogen gas

• Carbon dioxide

• Hydrogen gas

• Carbon monoxide

Combustion reactions are typically characterized by which of the following?

• Endothermic nature

• Exothermic nature

• Neutral pH

• Formation of solid products

What is the main cause of rust formation on metals?

• Exposure to sunlight

• Contact with oil

• Oxidation in the presence of moisture

• High temperatures

Which metal is commonly used in galvanization to prevent rusting?

• Zinc

• Aluminum

• Lead

• Copper

What is the purpose of painting metal surfaces?

• To enhance conductivity

• To prevent corrosion

• To increase weight

• To improve flexibility

According to the law of conservation of mass, what must be true in a chemical reaction?

• The mass of reactants is unrelated to the mass of products

• The mass of products is greater than the mass of reactants

• The mass of reactants is greater than the mass of products

• The mass of reactants equals the mass of products

In a balanced chemical equation, what is true about the number of atoms of each element?

• They are doubled on the product side

• They are halved on the reactant side

• They are equal on both sides

• They are only counted on the reactant side

What happens to the mass of individual elements during a chemical reaction?

• It increases

• It becomes zero

• It decreases

• It remains the same

Which of the following best describes the law of conservation of mass?

• Mass is conserved in chemical reactions

• Mass can be created or destroyed

• Mass is irrelevant in chemical reactions

• Mass is only conserved in physical changes