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