Abstract
This paper introduces a facile technique for the calculation of the thermodynamic properties of a gas across a porous membrane. The calculation assumes that the gas undergoes temperature-driven isobaric condensation, pressure-driven isothermal expansion and temperature-driven isobaric evaporation. The gas is in a disordered and chaotic state in all the three processes as a result of the kinetic energy by the driving forces. A zero entropy value is achievable at a remote distance from the membrane after desorption takes place. The deviation of the entropy from zero for isobaric evaporation is indicative of the irreversibility of the process. In contrast, the convergence of the entropy towards zero for the other two systems is indicative of the near-reversibility of the process.