Chemistry - the Complete Course Series, teaches students quantitative reasoning to solve chemistry problems. The 30 volume series covers all aspects of Chemistry from density to the mole, to molarity, stoichiometry and equilibrium. It demonstrates how to ask meaningful questions and conduct careful investigations to build knowledge of chemical and physical concepts and develop the skills to solve mathematical and scientific problems. In this program we take a close look at the hypothetical reaction 2A + B - C + 3D. Beginning with several different initial concentrations of reactants and products, we watch the system as it approaches and finally attains equilibrium. The single most important thing to understand about equilibrium is the form and nature of the equilibrium constant. This volume teaches that for every equilibrium system at a given temperature there exists a constant referred to as the equilibrium constant. When a reaction involves reactants or products that are pure solids or liquids, the form of the equilibrium constant expression must be modified. That after a period of time all concentrations become constant, indicating that the systems have achieved equilibrium.