A 5% solution of a reagent is required in the process of synthesis of a pharmaceutical intermediate. The solid reagent, available as crystals (density = 1580 kg/m3 ) of average particle size 0.75 mm, is dissolved in a stirred vessel to prepare 1.2 m3 solution in a batch. The requisite volume of water and the calculated quantity of solid are charged into a 1.15 m diameter tank fitted with a 0.6 m diameter impeller. Given: agitator rpm = 120; diffusivity of the solute = 1.5?10?5 cm 2 /s; average viscosity of the solution = 0.98 cP; solubility of the solid in water = 7.6 g per hundred gram water. Calculate the time required for the dissolution of the solid. The Sherwood number correlation in Example 3.4 (B. K. Dutta) can be used. (Solution density = 1000 kg/m3 )