Small spheres of solid benzoic acid are dissolved in water in an agitated tank. If the Sherwood number is nearly constant at a value of 4.0, show how the time for complete dissolution varies with the initial size of the particle. How much time would be required for 100-μm particles to dissolve completely in pure water at 25°C? Solubility: 0.43 g/100 g H₂O. D_v = 1.21 x 10^-5 cm²/s.