Momentum Artifacts in the Gravimetric Measurement of Rapid Desorption
When desorption rates are very rapid, a gravimetric balance responds to the momentum associated with the desorbing molecules as well as the weight loss. For a desorption time constant of 10−2/sec or greater, this momentum artifact can obscure the weight loss measurements. The equations for the response of the balance are solved and compared with propane desorption from activated charcoal, a system which exhibits a marked momentum error. It is shown that the artifact can be eliminated experimentally by using a wire mesh support pan and an appropriate amount of sorbent placed in the bottom of a tare hangdown tube to null out molecular drag.
KeywordsActivate Charcoal Gate Valve Adsorption Pressure Apparent Weight Liquid Nitrogen Trap
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