ABSTRACT
Natural and engineered systems often contain chemically reactive constituents. Mass transport of reactive substances differs from that of inert or nonreacting compounds because, by their action, chemical transformations alter or influence the local concentration of species involved with the reaction. Said another way, chemical transformations consume reactants and yield products, so reactive processes are coupled to the transport of individual chemical species. From the perspective of mass conservation, it is instructive to distinguish between two types of chemical reactions:
1. Homogeneous reactions. These are chemical reactions that take place at each point in the continuum. For a species A, they are quantified by the reaction rate RA (net moles of A produced at a point due to chemical reactions, per unit volume of medium) defined before. In general, RA depends on temperature and concentrations of all reactants that participate in reactions that produce or consume A.
