Sodium chloride (NaCl) diffuses through a film of water solution, 0.2 cm thick, at 20 c and 1 atm. The concentrations by weight on the 2 sides of the film are 12% and 5% respectively. Calculate: (1) The rate of diffusion of sodium chloride if its mass diffusivity in water is 1.51 x 105 cm /sec. (ii) If the sodium chloride and water are under equimolar counter diffusion, compute the diffusion coefficient. (4+4 =8)