1. The document introduces the concept of chemical equilibrium, including that it is a state where the concentrations of reactants and products do not change over time, and that forward and backward reactions continue at the microscopic level. 2. It describes the law of mass action, which states that the rate of a reaction is directly proportional to the product of the molar concentrations of reactants raised to their stoichiometric coefficients. 3. It provides expressions for calculating equilibrium constants (Kc) in both gaseous and liquid/solid systems based on the law of mass action and reaction stoichiometry.