2. A spherical time-release capsule was developed to release pesticide to surrounding soil, as shown in the figure below. The capsule is 1.0 cm in diameter, and is made of a polymer containing a uniform initial concentration of pesticide (species A) equal to 2.0 mg/cm'. The effective diffusion coefficient (DA) of the pesticide in the polymer is 5.0 x 10 cm-/s. During wet periods of the year, water flows into the loose soil and slowly flows around the buried capsules, creating a boundary layer that provides a convective mass transfer coefficient (k.) of about 1.0 x 10-6 cm/s. The bulk concentration of pesticide in the flowing water is very small, and so can be considered as effectively equal to zero (CA. = 0). The molecular diffusion coefficient of the pesticide in water (DAB) is 1.0 x 10-6 cm/s (A = pesticide, B = water). a. What is the concentration of pesticide in the center of the capsule after a time of 173.6 h? b. What is the concentration of pesticide at the surface (r=R) of the capsule after 173.6 h, and what is the flux of pesticide out of the particle, N.(R.1), at this time, in units of mg/cm's? Water flow (v.) Groundwater flow CA = 2.0 mg/cm D = 5x 10 cm/s Pesticide-filled polymer capsules (1.0 cm diameter) buried in loose soil CAS CA-- 0