This textbook summarizes the fundamentals of mass balances as the approach that provides a global vision of the process for chemical, environmental and bioprocess engineers. Many examples of calculations, diagrams and flow charts facilitate understanding. The book proposes an original methodology based on the intensive application of the spreadsheet. This approach introduces the concept of "simulation" which allows to determine the effect of operating parameters on individual units but also on entire processes. Case studies on relevant topics such as sustainable chemistry illustrate the theory behind current applications. Fundamentals of mass balances in systems with and without chemical reactions, Easy to understand with plenty of examples of calculations, diagrams and flow charts, Examples of current practices in the field of sustainable chemistry, Intensive application of the spreadsheet as a methodology for calculating and simulating units and processes Book jacket.