A tube 2m in length and 10^-4m^2 in cross section contains a 50%-50% mixture of 14CO2. CO2 (g) has a diffusion coefficient, D = 7.1*10^-6 m^2 s^-1, at1 atm and 273K. At t=0, all of the molecules at the left end of the tube are 14CO2 and the number of 14CO2 per unit volume decreases uniformly to zero as one approaches the right end of the tube.
1. Find out the initial concentration gradient of 14CO2 molecules?
2. Determine the initial net rate of 14CO2 diffusion across the cross section of the tube in molecules s^-1?