What is activation energy and how does temperature influence the rate of a reaction?

• A. Activation energy is the maximum energy for a reaction; increasing temperature decreases kinetic energy.
• B. Activation energy depends on the catalyst alone.
• C. Activation energy is the minimum energy for a reaction; increasing temperature increases kinetic energy, leading to more successful collisions.
• D. Activation energy is irrelevant to reaction rate.

Answer: (C)

Activation energy is the minimum energy that reacting particles must have to break bonds and start forming products. When molecules collide, they need enough energy and the right orientation to react. Temperature raises the average kinetic energy of the molecules, so a larger portion of collisions have energy above that minimum. More successful collisions per second means the reaction rate increases. This fits with the idea that higher temperature makes it easier for particles to overcome the energy barrier, speeding up the reaction.

What about the other ideas? Activation energy isn’t a maximum energy, so that part is incorrect. Temperature doesn’t decrease kinetic energy; it increases it. The Ea isn’t set by the catalyst alone—the catalyst lowers the energy barrier to make reactions easier but doesn’t define it for the uncataylzed path. And activation energy is not irrelevant to rate; it’s a central factor that temperature can help particles overcome.