A gas of methane and helium is contained in a tube at 101.32 kPa and 298 K. At one point the partial pressure of methane is pA1=60.79 kPa and at a point 0.02 m away pA2 = 20.26 kPa. If the total pressure is constant throughout the tube, calculate the flux of methane at steady state (for equal molar counterdiffusion). The diffusion coefficient of methane through helium is 0.371 cm2/s at 200 K and can be assumed to be proportional to the temperature raised to the 3/2 power.