.3 Derive an expression to represent the overall fugacity coefficient of the mixture, mix, as follows: (a) Start with Gmix=i=1kxiGi and show that Gmix=i=1kxii+RTi=1kxilnfi (b) The fugacity of the mixture, fmix, is defined by Gmix=mix+RTlnfmix with the following constraint: mix=fmix/P1asP0 Equate Eqs. (2) and (3) to get mix+RTlnfmix=i=1kxii+RTi=1kxilnfi Since Eq. (5) is valid at all pressures, evaluate Eq. (5) as P0 to conclude that mix=i=1kxii+i=1kxilnxi (c) Show that the use of Eq. (6) in Eq. (5) leads to lnmix=i=1kxilni or mix=i=1kixi