The purification of hydrogen gas is possible by diffusion through a thin palladium sheet. Calculate the number of kilograms of hydrogen that pass per hour through a 6.0-mm-thick sheet of palladium having an area of 0.18 m2 at 500°C. Assume a diffusion coefficient of 4.7 × 10-8 m2/s, that the concentrations at the high- and low-pressure sides of the plates are 2.6 and 0.72 kg/m3 of hydrogen per cubic meter of palladium, and that steady-state conditions have been attained.