To measure the diffusion coefficient, DAB, of a He-N2 gas mixture, two tanks are connected through a small cylindrical tube that is L = 15 cm long and 0.1 cm in diameter. Initially Tank 1 (V1 = 100 cm3) contains only He gas and Tank 2 (V2 = 300 cm3) contains only N2 gas. The two tanks are maintained at a constant temperature of 80°C and a constant pressure. The mole faction of He (gas A) in Tank 2 is measured with a gas chromatograph as a function of time. The data during the first 100 hours of the experiment, along with the best-fit line through them, are shown in Figure.