6.4 Chemical energy

What is the concept that states that the total mass of reactants equals the total mass of products in a chemical reaction?

• Conservation of mass
• Conservation of energy
• Law of thermodynamics
• Law of conservation of matter

Which of the following is an example of a physical change?

• Burning wood
• Boiling water
• Rusting iron
• Cooking an egg

What determines whether a reaction is exothermic or endothermic?

• The concentration of reactants
• The temperature of the surroundings
• The difference in energy transferred in bond making and bond breaking
• The presence of a catalyst

Which of the following is an example of an exothermic change?

• Burning wood
• Boiling water
• Dissolving salt in water
• Melting ice

What is the product of the reaction between nitrogen and oxygen in a car engine?

• Carbon dioxide
• Nitrogen monoxide
• Oxygen gas
• Water vapor

What is the energy transfer in bond making?

• Energy is transferred to the reactants
• No energy transfer occurs
• Energy is transferred to the surroundings
• Energy is transferred from the surroundings

What is an endothermic reaction?

• A reaction where no energy is transferred in bond making and bond breaking
• A reaction where the energy needed to break bonds is more than the energy released on making new bonds
• A reaction where the energy needed to break bonds is less than the energy released on making new bonds
• A reaction where the energy needed to break bonds is equal to the energy released on making new bonds

Which of the following is a damaging effect of exhaust pollutants?

• Improved air quality
• Enhanced human health
• Negative impact on human health and the environment
• Reduced environmental impact

Which of the following is an example of an exothermic change in everyday life?

• Burning paper
• Evaporating water
• Mixing salt in water
• Melting chocolate

What is the process that occurs in a cold pack?

• Freezing
• Combustion
• Dissolving
• Condensing