b) A preparation of drug granules weighing 5.5g and having a total surface area of 2.8103cm2 dissolves in 500mL of water at 25C. The quantity of drug dissolved after the first minute is 0.38g, the saturated solubility of the drug is 10mgmL1 and the diffusion layer thickness is 2.5103cm. Using the Noyes-Whitney equation, calculate: i) the dissolution rate constant ii) the diffusion coefficient iii) the effect on the dissolution rate of an increase of surface area to 5103cm2