These various little experiments with an aqueous system illustrate some rate behavior with common factors such as concentration, temperature and catalysts. There are other factors as well which we mentioned in class. In reactions where solids are involved surface area is certainly an important factor. Subdividing the solid (e.g. grinding it to a powder) is a way of exposing more surface to collisions. Predictably, this generally results in an increase in reaction rate.

When gases are involved pressure is likewise an important factor with behavior analogous to solution concentration. High pressure forces molecules closer to one another and as the opportunity for collision increases, so too (generally) does the rate.