Book excerpt: A thorough introduction to balance equation concepts. Geared for the course offered to chemical engineering majors in their sophomore year. Develops a framework for the analysis of flowsheet problem information with extensive use of degree-of-freedom analysis. Presents systematic approaches for manual and computer-aided solution of full scale balance problems. Provides a detailed development of the structure, properties, and interrelationships of species and element balances based on the algebraic view of reaction-stoichiometry and the rate of reaction concept.