HS-PS1-4: Chemical Reactions and Energy Quiz

What happens to bond energy when chemical bonds are broken?

• Energy is absorbed

• Energy is released

• The reaction becomes exothermic

• Atoms disappear

What happens to bond energy when chemical bonds are formed?

• Energy is absorbed

• Energy is released

• The reaction becomes endothermic

• New atoms are created

Which of the following describes an exothermic reaction?

• The products have more energy than the reactants

• Energy is absorbed

• More energy is released when bonds form than is absorbed when bonds break

• The temperature of the surroundings decreases

Which of the following is an example of an endothermic process?

• Burning a candle

• Freezing water

• Melting ice

• Condensation of water vapor

What is the primary factor that determines whether a chemical reaction absorbs or releases energy?

• The change in mass of the reactants

• The balance between bond-breaking and bond-forming energy changes

• The speed of the reaction

• The amount of reactant used

Which type of reaction would likely feel cold to the touch?

• Exothermic

• Endothermic

• Combustion

• Neutralization

In a chemical reaction, the energy required to break bonds in the reactants is 500 kJ, and the energy released when new bonds form is 650 kJ. What type of reaction is this?

• Endothermic

• Exothermic

• Neutralization

• It is at equilibrium

In an endothermic reaction, where does the absorbed energy come from?

• The products

• The chemical bonds

• The surroundings

• Nowhere—it is created during the reaction

Which of the following would be an indicator of an exothermic reaction?

• A decrease in temperature

• Light or heat being emitted

• The reaction container getting colder

• Energy being absorbed from the surroundings

Why do exothermic reactions release energy?

• Because forming new bonds releases more energy than breaking old bonds

• Because all reactions release energy

• Because reactants always have more energy than products

• Because reactants lose mass