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trnsport of Co, Through Rubber. A flat plug 30 mm thick having an area of 4.0 ×

ID: 553927 • Letter: T

Question

trnsport of Co, Through Rubber. A flat plug 30 mm thick having an area of 4.0 × 10-4 m2 and made of vulcanized rubber is used for closing an opening in a con- tainer. The gas CO2 at 25°C and 2.0 atm pressure is inside the container. Calculate the total leakage or diffusion of CO2 through the plug to the outside in kg mol CO2/s at steady state. Assume that the partial pressure of CO2 outside is zero. From Barrer (B5) the solubility of the CO2 gas is 0.90 m2 gas (at STP of 0°C and 1 atm) per m3 rub- ber per atm pressure of CO2. The diffusivity is 0.11 × 10-9 m2/s.

Explanation / Answer

L = 30 / 1000 = 0.03 m, Area is given = 4 x 10-4 m2 ; diffusivity = 0.11 x 10-9 m2/s; S = 0.9 m3

concentration1 = s * P1 / 22.44 = 0.9 m3 * 2 atm / 22.44 = 0.08021 Kgmol / m3 rubber

concentration 2 is 0, this is because pressure 2 is zero

NA / A = DAB * (ca1 - ca2) / (z2 - z1); z2 - z1 is the distance traveled, in this case this value is 0.03; A is area

NA / 4x10-4 = DAB * (ca1 - 0) / 0.03

NA = 0.11 x 10-9 * 4x10-4 * 0.08021 / 0.03 = 1.176 x 10-13 Kgmol / seg