Let us introduce the idea of chemical equilibrium by an analogy, seemingly far-fetched at first sight, but actually mathematically correct. Imagine that a crabapple tree sits on the dividing line between two homes, one inhabited by a crochety old man, and the other by a father who has told his young son to go out and rid the back yard of crabapples. The boy quickly realizes that the easiest way to dispose of the crabapples is to throw them into the neighbouring yard. He does so, arousing the ire of the old man.

The boy and the man start throwing crabapples back and forth across the fence as fast as they can. Who will win?


The battle is outlined in five phases, as shown on the following pages.