[填空题]
Oxygen diffuses from the surface ofyxeltin .38dl1x(3rv insects to the interior wn-)fsyyyr9k (xj 7fel78 52 3xr/+mffsxi knthrough tiny tubes called tracheae. An average trachea is about 2 mm long and has cross-sectional a/-(yffx 72e rjxy7l nwx3k) k+i8ss 9fmnrf5yrea of Assuming the concentration of oxygen inside is half what it is outside in the atmosphere,
(a) show that the concentration of oxygen in the air (assume 21% is oxygen) at 20 C is about 8.7 mol/ then mol/(Round to one decimal places)
(b) calculate the diffusion rate J, mol/s
(c) estimate the average time for a molecule to diffuse in. Assume the diffusion constant is s