Why does decreasing the temperature of the reactants generally result in a slower reaction rate?

• A. Because the products become less stable at lower temperatures.
• B. Because fewer reactant molecules have enough kinetic energy to overcome the activation energy barrier.
• C. Because the activation energy of the reaction increases at lower temperatures.
• D. Because the concentration of reactants decreases as temperature decreases.

Answer: (B)

Verified step by step guidance

1. Understand that reaction rate depends on how often and how effectively reactant molecules collide.
2. Recall that temperature is directly related to the average kinetic energy of molecules; higher temperature means molecules move faster.
3. Recognize that for a reaction to occur, reactant molecules must have enough energy to overcome the activation energy barrier, which is the minimum energy needed for the reaction to proceed.
4. At lower temperatures, fewer molecules have kinetic energy equal to or greater than the activation energy, so fewer successful collisions occur.
5. Therefore, decreasing temperature reduces the number of effective collisions, leading to a slower reaction rate.