A 5 in long plastic tube with an outer diameter of 8 min and a wall thickness of 1 mm is used to deliver N2 at 1 atm pressure to a furnace in a...

A 5 m long plastic tube with an outer diameter of 8 mm and a wall thickness of

1 mm is used to deliver N2 at 1 atm pressure to a furnace in a laboratory. Oxygen

molecules can dissolve into the plastic when it is exposed to room temperature

air. As O2 molecules diffuse across the the wall of the tubing, oxygen is

introduced into the otherwise pure N2 gas stream, which flows to the furnace at

a rate of 0.1 1/s. The diffusivity of O2 in the plastic is 10-12 cm2/s at room temperature.

At the outer surface of the tube, O2 is incorporated into the plastic at a

rate consistent with a first order chemical reaction: j = k·p(O2) with a rate constant

k = 1010 molecules/(cm2·s·atm) and p(O2) = 0.2 atm for air.

a) Estimate the difference in oxygen concentration within the plastic across the

wall of the tubing.

b) Determine the concentration in parts per billion (ppb) of O2 present in the

gas stream as it enters the furnace.

A 5 in long plastic tube with an outer diameter of 8 min and a wall thickness of1 mm is used to deliver N2 at 1 atm pressure to a furnace in a laboratory. Oxy—gen molecules can dissolve into the plastic when it is exposed to room tempera—ture air. As 02 molecules diffuse across the the wall of the tubing. oxygen isintroduced into the otherwise pure N2 gas stream, which flows to the furnace at a rate of 0.1 Us. The diffusivity of O; in the plastic is 10-12 cmzfs at room tem— perature. At the outer surface of the tube, 02 is incorporated into the plastic at arate consistent with a first order chemical reaction: j = k -p(02) with a rate con—stant k 2 10'1“ nloleculesflcrnl-s-atin) and pEOg) = 0.2 atln for air. a) Estimate the difference in oxygen concentration within the plastic across the wall of the tubing.b) Determine the concentration in parts per billion (ppb} of 02 present in the gas stream as it enters the furnace.