-4. Diffusion of Methane Through Nondiffusing Helium. Methane gas is diffusing in a straight tube 0.1 m long containing helium at 298 K and a total pressure of 1.01325 x 105 Pa. The partial pressure of CH at one end is 1.400 × 104 Pa and 1.333 x 103 Pa at the other end. Helium is insoluble in one boundary, and hence is nondiffusing or stagnant. The diffusivity is given in Table 6.2-1. Calculate the flux of methane in kg mol/s m² at steady state.