Question 1: Mass transfer from a packed bed of spheres An aqueous solution at a temperature of 299.25 K flows through a column having a packed bed made up of benzoic acid spheres. The benzoic acid spheres have a diameter Dp = 8 x 10' m and the superficial velocity of the aqueous solution through the packed bed is 0.01 m/s. The packing porosity or voidage is 0.5. The solubility of benzoic acid in the aqueous solution at 299.25 K is 2.9474 x 10-2 kmol/m. If the inlet concentration of the aqueous solution is 1 x 10-4 kmol/m' and its exit concentration is 3 x 10.2 kmol/m, (a) determine the convective mass transfer coefficient, k. [7 marks] (b) determine the molar flux, Na, after assuming that k' = kc [3 Marks] = Data given: DAB = 1.254 x 10-9m2/s Density of the solution, p = 994 kg/m3 Viscosity of the solution, u = 1 x 10-3 Pa.s