What is the energy required to start a chemical reaction called?

• A. Activation energy
• B. Kinetic energy
• C. Chemical energy
• D. Potential energy

Answer: (A)

Activation energy is the energy barrier that must be overcome for reactants to reach the transition state and form products. It represents the minimum energy input needed to break and rearrange bonds so the reaction can proceed. Temperature increases can supply more kinetic energy to molecules, helping more collisions overcome this barrier, and catalysts work by lowering the barrier itself. Kinetic energy is just the energy of motion and plays a role in whether collisions have enough energy, but it isn’t the barrier. Chemical energy is the energy stored in bonds that may be released or required during the reaction, and potential energy is the stored energy due to position; both describe energy changes during the reaction, while the activation energy specifically describes the required energy to start it.