Carbon dioxide diffuses through a high-density polyethylene (HDPE) sheet 50 mm thick at a rate of 2.2

Question:

Carbon dioxide diffuses through a high-density polyethylene (HDPE) sheet 50 mm thick at a rate of 2.2 × 10-8(cm3STP)/cm2-s at 325 K. The pressures of carbon dioxide at the two faces are 4000 kPa and 2500 kPa, which are maintained constant. Assuming conditions of steady state, what is the permeability coefficient at 325 K?