Is the reaction rate affected by surface area?

1 Answer
Jun 2, 2018



Surface area is one of the factors that affect the rate of reaction. The reason for that is simple.

First, do an experiment demonstrating the effect of surface area to the rate of reaction. I'll use an acid-metal reaction for simplicity.

The apparatus you would need for this experiment are:

  • Some magnesium ribbons

  • Dilute hydrochloric acid #(HCl)#

  • Gas syringe (optional)

  • Stopwatch

  • Beaker or test tube, but beaker preferred

Take a piece of magnesium metal and some dilute hydrochloric acid. Now, put the strip of magnesium metal into the acid. Record how much time does it take for the reaction to stop producing bubbles.

Now, repeat the experiment, but cut the magnesium ribbon into strips of equal size, thus increasing its surface area. Again, add them to the acid. Record the time that it takes for the reaction to stop producing bubbles like the previous procedure. Now, compare your results with the last time.

The latter experiment should have a much faster reaction time.

This is because when there is a large amount of surface area, there is more chance of acid particles hitting the magnesium metal, hence the frequency of collisions increase, and the overall reaction rate increases.

You might want to watch a video about the effect of surface area on the rate of reaction: