A steady state diffusion is used to purify hydrogen gas by passing through a selective metal plate at a certain temperature. Compute the number of kilograms of hydrogen that passes per hour through this plate, which has a thickness of t mm and an area of Am^2 . The diffusion coefficient of hydrogen at that temperature in that metal is D m^2/s . The concentrations of hydrogen on the high pressure and low pressure sides of the metal plate are C1 and C2 kg per cubic meter, respectively