Use particle models to explain why increasing temperature can increase the rate of reaction.

• A. The color changes indicating faster reactions.
• B. Energy decreases as temperature increases.
• C. The number of particles increases.
• D. As we heat the reactants, the particles gain energy and move faster, which leads to more collisions between particles.

Answer: (D)

Temperature affects reaction rate by changing how the particles move and how much energy they have. When temperature rises, particles gain kinetic energy and move faster, so they collide more often. A higher temperature also shifts the energy distribution so a larger portion of those collisions have enough energy to overcome the activation energy, making more collisions productive. With both more collisions and more energetic collisions, the reaction proceeds faster.