摘要：The extent of a chemical reaction has received little attention in the early stages of Chemistry teaching, despite allowing a general way to work with chemical reactions and equilibria. In this article, the concepts of extent of reaction and extent of reaction balances are revised and several applications to study the change in the concentrations of the species involved in chemical reactions are described for both single and multiple systems. Extent of reaction balances allow a general treatment that can be applied to problems of diverse complexity involving different types of equilibria, either in the gas phase or in solution (acid-base, complexation, precipitation and redox reactions). This treatment depends exclusively on the reactions stoichiometry and can be taught at several levels, for single or coupled equilibria. Several examples are given, from basic problems adequate for High School Chemistry to problems for College Chemistry.
关键词：high school chemistry; first- and second-year undergraduate; chemical education research / applications of chemistry; problem solving; aqueous solution chemistry / equilibrium
