A gas mixture containing nitrogen is refractory with an inner radius (R1) of 4 cm and an outer radius (R2) of 6 cm. diffuses through a spherical tube contained in a glass tube. radial between R1 and R2 At steady state, where nitrogen diffuses through the spherical shell of thickness r at position Its concentration on the inner surface is 12 mol/L, and its concentration on the outer surface is 16 mol/L. The diffusion coefficient is 2x10-4 m2/s. Derive the concentration profile by establishing a shell equilibrium and find the concentration and flux of nitrogen at r=5 cm.