mass transportation problem

Discussion in 'Homework Help' started by Neomaster, May 5, 2009.

  1. Neomaster

    Thread Starter New Member

    May 5, 2009
    I have this following problem and I don't know where to start. Can you guys help me? Thanks!

    Am cubic (1m³) container of polyethylene, wall thickness 2mm, contains pure oxygen (O2) at 1.5 atm and 20°C. The container is placed in ambient air (21% O2 and 79% N2) at 1 atm and 20°C.
    Estimate the total pressure and gas composition after:
    a.) 1 month
    b.) 1 year
    c.) 5 years.

    The mass diffusion flux can be written as j_1= (P_12/L)*(p_1,0 - p_1,L)

    The mass flux out of the container equals the change of mass per unit time in the container.
    j=-1/A *dm/dt
    Ideal gas law: pV = mRT


    I tried to apply Fick's second law, but I have no idea about the boundary conditions.