In this paper, we propose a complementary strategy to introduce electrochemical cells in introductory courses of chemistry. Frequently some of the concepts related to electrochemical processes, such as electric work, reversible and irreversible changes, maximum work and differences and similarities between galvanic and electrolytic cells among others, are poorly developed in this kind of courses. We propose, for the introductory treatment of these concepts, an analogy between isothermal expansion of a perfect gas and an electrochemical process. The analogy is qualitatively and quantitatively discussed