A droplet of liquid A of radius r1 is suspended in a stream of gas B shown below. We postulate that there is a spherical, stagnant gas film of radius r2 surrounding the droplet. The concentration of A in the gas phase is xA1 at r = r1 and xA2 at the outer edge of the film r = r2.

A droplet of liquid A of radius r1 is suspended in a stream of gas B shown below. We postulate that there is a spherical, stagnant gas film of radius r2 surrounding the droplet. The concentration of A in the gas phase is XA1 at r=r1 and XA2 at the outer edge of the film r=r2. (a) Use conservation of mass to show that the flux of species A in the gas film is: r21drd(r2NA,r)=0 Is the flux constant throughout the film? Why or why not? (Think about geometry). (b) Use the expression for the molar flux NA,r (including convection and diffusive terms) to show that the concentration profile in the film satisfies the following differential equation r21drd(r2drd[ln(1xA)])=0 State the boundary conditions. Do not attempt to solve the ODE