In: Chemistry
A gas mixture at a total pressure of 144 kPa and 327 K contains 11% H2, 40% O2, and the rest H2O by volume. The absolute velocity of each species are −6, −3, and 12 m/s, respectively, all in the direction of the z-axis. Determine (a) the mass diffusion flux of O2 and (b) the molar diffusion flux of O2.
Total pressure = 144kPa
Temperature = 327K
Total volume = 100 Kg moles of gas
Volume of H2 = 11mol
Volume of O2 = 40mol
Volume of H2 O = 100mol - ( 11mol + 40mol) = 49mol
Molar flux for a specie X formula is
Nx = Cx Vx Where N is the molar flux, C is the molar concentration and V is the velocity
But C = moles of the gas / total volume
Molar concentration of O2 - C = 40 / 100 = 0.4 Kg mol
Absolute velocity of O2 = 12m/s
So Molar diffusion flux of O2 No2 = 0.4 12 m/s = 4.8 mol m / s
Mass diffusion flux formula for species X is
nx = x Vx where n is the mass diffusion flux, is the mass concenteation and V is the velocity
But = mass of the element / volume
Mass of oxygen = 16
so for oxygen o2 = 16 / 100 = 0.16 Kg mol
So mass diffusion flus for oxygen no2 = o2 Vo2 = 0.16 12 = 1.92 Kg mol m / s