4. Benzoic acid is a solid at 300K and is soluble in water. 100g of solid benzoic acid spheres, with a total interfacial area of 2300cm2 are dropped into an agitated stirred tank containing 10 litres of pure water. After 10min, the benzoic acid concentration in the water is 0.3mg/cm3 (i) Write mass balance on benzoic acid in the solution and determine a value for the mass transfer coefficient under the stated conditions. Assume that the interfacial area does not change significantly during this time. [60%] (ii) If the initial agitation rate was higher, so that the mass transfer coefficient was a factor four higher than that in part (i), what would be the concentration of benzoic acid after 10 minutes? [40\%] Data: Solubility of benzoic acid in water =3mg/cm3