Problem $1(1$ pt$).$ Write out the continuity equation in general terms for molar$-$based fluxes and

concentrations. Develop this equation into a form specific to the situation where A diffuses

through B and decays at a rate proportional to the concentration of A $($first order decay$).$ The

concentration has reached a steady state; remove the appropriate term. Reduce to one

rectilinear dimension; remove the extra dimensions.

Problem $2(2$ pt$).($a$)$ Write out the fully general equation for flux $($or A through B$)$ in molar units.

It will start with $N_A$ and then it will contain the molecular diffusion part and the convection part.

See lecture $15.$

$($b$)$ Does $N_B$ still matter if $A$ is dilute? $($yes or no$)$