Advanced Placement (AP) Biology Practice Exam

What does chemical energy allow a substance to do?

1. Exist in a solid state

2. Undergo a chemical reaction and transform

3. Move quickly and generate heat

4. Be stored indefinitely without change

The correct answer is: Undergo a chemical reaction and transform

Chemical energy is the energy stored in the bonds of chemical compounds, like atoms and molecules. This energy plays a critical role in allowing substances to undergo chemical reactions and transform into different products. When a chemical reaction occurs, bonds between atoms are broken, and new bonds are formed, resulting in the transformation of substances. For example, in a combustion reaction, the chemical energy stored in hydrocarbons is released and converted into heat and light energy. Therefore, the ability of a substance to transform through chemical reactions is a direct consequence of its chemical energy. The other options do not accurately reflect the role of chemical energy. While a substance's state can be influenced by temperature and pressure, the existence of a substance in a solid state is not directly a result of its chemical energy. The speed of movement and generation of heat pertains more to kinetic energy rather than chemical energy. Lastly, while some substances can be stored without change for longer or shorter periods, they are subject to specific conditions that may eventually lead to reactions if the conditions are right, contradicting the idea of indefinite storage without change.