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Sources of Error in Sorption and Density Measurements


In sorption measurements, volumetric or gravimetric procedures are commonly used to determine the amount adsorbed. At low pressures, thermomolecular flow and pressure differences according to Knudsen's law disturb measurements. In volumetry, calibration of the dead space is required; in gravimetry, the influence of buoyancy has to be taken into account. In both cases, adsorption of the calibrating gas, usually helium, may disturb the measurements [1]. From the calibration measurements, the density of the sample can in principle be calculated. However, it has been observed in many experiments that its value depends on the calibrating gas.

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Robens, E., Keller, J.U., Massen, C.H. et al. Sources of Error in Sorption and Density Measurements. Journal of Thermal Analysis and Calorimetry 55, 383–387 (1999).

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  • buoyancy
  • density
  • helium
  • Knudsen effect
  • mass determination
  • sorption
  • thermomolecular flow