  Entropy generation in a chemical reaction is analyzed without using the
general formalism of non-equilibrium thermodynamics at a level adequate for
advanced undergraduates. In a first approach to the problem, the
phenomenological kinetic equation of an elementary first order reaction is used
to show that entropy production is always positive. A second approach assumes
that the reaction is near equilibrium to prove that the entropy generated is
always greater than zero, without any reference to the kinetics of the
reaction. Finally, it is shown that entropy generation is related to
fluctuations in the number of particles at equilibrium, i.e. it is associated
to a microscopic process.
