Activation energy

Activation energy

• A. The maximum energy of products.
• B. The minimum energy required for a molecule to react.
• C. The energy difference between reactants and products.
• D. The energy released in the reaction.

Answer: (B)

Activation energy is the energy barrier that must be overcome for reactants to reach the transition state and proceed to products. This is the minimum kinetic energy a molecule needs to react, so the statement that activation energy is the minimum energy required for a molecule to react is the best fit. It’s different from the energy difference between reactants and products (the overall ΔH, which tells you if the reaction is exothermic or endothermic) and from the energy of the products themselves or the energy released. Temperature raises the fraction of molecules with enough energy to get over the barrier, and catalysts lower the barrier, speeding up the reaction.

Activation energy is the energy barrier that must be overcome for reactants to reach the transition state and proceed to products. This is the minimum kinetic energy a molecule needs to react, so the statement that activation energy is the minimum energy required for a molecule to react is the best fit. It’s different from the energy difference between reactants and products (the overall ΔH, which tells you if the reaction is exothermic or endothermic) and from the energy of the products themselves or the energy released. Temperature raises the fraction of molecules with enough energy to get over the barrier, and catalysts lower the barrier, speeding up the reaction.