01Effective collisions
Particles react only if they collide with enough energy (≥ activation energy) and the right orientation.
Raising T increases both collision frequency and, much more importantly, the fraction of collisions above Ea.
02Notebook box
Higher T → more molecules past Ea on the Maxwell–Boltzmann curve → k increases.
Worked example: Why does refrigeration slow spoilage? Fewer collisions exceed Ea.