How does the rate of reaction affect the surface area?
The rate of a chemical reaction can depend on the surface area of reactants. The speed of a chemical reaction depends on how quickly the reactants can collide with each other.
When reactants can bump into each other more quickly, they will react more quickly.
Watch the video below to compare how fast the powder burns when it is in a pile compared with how quickly it burns when suspended in the air.
Video from: Noel Pauller
The powder has less surface area exposed to collisions with oxygen when it is in the pile, so it burns more slowly.
When the powder is suspended in the air, it is spread out and has much more surface area. This allows for more frequent collisions with oxygen and a much greater speed of reaction.
Hope this helps!