Write the integral equation for a fixed control volume \(\Omega\) that expresses the principle of conservation of chemical species described in Section 2.2.2.

Let us now assume that the fluid is a composition of several chemical species, which can transform into each other by chemical reactions. A good example is the flow in a combustion chamber, where a mixture of a hydrocarbon fuel and air is burned to produce exhaust products and energy. The law of conservation of mass still holds, of course, but Eqs. (2.5) and (2.6) have to be modified to account for chemical reactions and interspecies diffusion. The diffusion is, to put it simply, a process of spontaneous transport of chemical species from the location where their relative concentration is high