where R is the gas constant, n the total number of moles and x i the mole fraction of component i , which initially occupies volume V i = x i V . After the removal of the partition, the n i = n x i moles of component i may explore the combined volume V , which causes an entropy increase equal to n x i R ln ⁡ ⁡ ( V / V i ) = − − n R x i ln ⁡ ⁡ x i for each component gas.