What happens to bonds during a chemical reaction?

• They remain unchanged.

• They are broken and reformed.

• They dissolve in water.

• They become stronger.

What is thermal energy in the context of exothermic reactions?

• Energy absorbed from the surroundings.

• Energy produced by the reaction.

• Energy stored in the reactants.

• Energy lost to the environment.

What is the role of energy in breaking and reforming bonds?

• Energy is always absorbed.

• Energy is always released.

• Energy is either absorbed or released.

• Energy is not involved.

What is the primary source of energy in an exothermic reaction?

• The environment

• The chemical bonds of reactants

• The products

• The catalyst

What is the effect of energy changes during a chemical reaction?

• Change in color

• Change in temperature

• Change in shape

• Change in mass

What is a common use for heat packs mentioned in the text?

• Cooling down

• Warming muscles

• Generating electricity

• Lighting a room

What is the state change involved in some exothermic processes?

• Solid to gas

• Gas to liquid

• Liquid to solid

• Solid to liquid

How long can the energy from the chemical reaction keep the pack warm?

• Up to 5 hours

• Up to 10 hours

• Up to 20 hours

• Up to 30 hours

What is an exothermic process that is not a chemical reaction?

• Formation of new substances

• Rearrangement of compound molecules

• Absorption of heat

• Cooling of substances

What substance is commonly found in pocket warmers sold in camping stores?

• Calcium chloride

• Sodium chloride

• Sodium acetate

• Potassium nitrate