Stoichiometry is the study of quantitative relationships between substances involved in chemical changes. That the Universe is a constantly changing place is readily apparent from any walk down the street. People and cars pass by, the sky is filled with moving clouds, the businesses and storefronts keep changing, and everything seems to be in motion. It is, in some ways, surprising that ancient philosophers often argued for the permanence of the Universe and unchanging nature. Some even argued against motion itself, saying it was but an illusion. In many ways, these thought experiments inhibited the development of science. But in understanding the constant nature of the Universe, they were right; just not in the way that they thought.

Underlying chemistry are a number of principles or laws that provide the basis for the relationships between the reactants and products in a chemical reaction. This relationship, called...