6.2 Energy in Chemical Reactions

What is one of the most important features of chemical reactions?

• They produce large amounts of energy.

• They produce large amounts of water.

• They produce large amounts of oxygen.

• They produce large amounts of carbon dioxide.

What form of energy do all molecules store?

• Kinetic energy

• Thermal energy

• Chemical potential energy

• Electrical energy

What happens to atoms and molecules during chemical reactions?

• They remain the same

• They disappear

• They rearrange and release energy

• They become larger

What type of reaction is it usually if a chemical reaction has oxygen as a reactant?

• Endothermic

• Exothermic

• Neutral

• Catalytic

What is an example of a combustion reaction that releases heat?

• Ice melting

• Water boiling

• Fire burning

• Photosynthesis

What is a combustion reaction?

• A. A reaction where a substance burns in oxygen to produce light and heat.

• B. A reaction where a substance dissolves in water.

• C. A reaction where a substance freezes.

• D. A reaction where a substance evaporates.

What type of reaction is a fire an example of?

• A. Combustion reaction

• B. Freezing reaction

• C. Dissolution reaction

• D. Evaporation reaction

What does a combustion reaction release?

• A. Light and heat

• B. Cold and darkness

• C. Water and ice

• D. Smoke and fog

What are the two elements that make up hydrocarbons?

What is the product of the combustion of a hydrocarbon in the presence of oxygen?

• CO₂ and H₂O

• CO and H₂

• C and H₂O

• CO₂ and O₂