Why does increasing surface area increase rate of reaction?

• A. More exposed particles can react
• B. Temperature rises
• C. More activation energy
• D. Fewer particles collide

Answer: (A)

Increasing surface area exposes more of the reactant to the other reactant, creating more sites where collisions can occur. In reactions that happen at surfaces, collisions at these sites are what drive the reaction, so more exposed area means more frequent effective collisions per unit time. That boost in collision frequency speeds up the rate. The other options describe changes that aren’t caused by surface area: higher temperature increases energy of collisions, not contact points; higher activation energy makes it harder for collisions to succeed; and fewer collisions would slow the rate.