Ethanol is diffusing through a 4-mm stagnant film of water. the ethanol concentrations at the entrance and the existing planes are maintained at 0.1 and 0.02 mol/m3, respectively. if the water film temperature is kept constant at 283 k determine the steady-state molar flux of the ethanol and the concentration profile as a function of the position z within the liquid film. compare these results with a 4-mm stagnant film of air at 283 k and 1 atm at the same entrance and exit ethanol concentrations.