Page 142 - Gas Adsorption Equilibria

128 Chapter 3

and (cp. (3.21))

Here we have assumed helium to be an ideal gas, i. e.

Quantities and parameters to be measured and their dispersions are listed
in the table below:

Here the symbol indicates any of the electromagnetically measured
mechanical moments occurring on the r. h. s. of eq. (3.10), the uncertainties of
which having been assumed to be equal for all four types of
measurements mentioned above, cp. Sect. 2.1.2.

From (3.18), (3.19) one can recognize that the MSD of the Gibbs excess
mass will increase with increasing numerical values of the reduced
mass of the adsorbate (3.5), (3.10) and – of course – with increasing MSD of
the moments’ measurements Hence it is very important to know
system’s parameters fairly accurately, i. e. the relative uncertainties
should be Modern two beam microbalances, cp.
Tab. 3.1, allow measurements with relative uncertainties of moments
Combined with accurate measurements of sorptive’s
gas pressure indicating the maximum pressure
measurable with the manometer considered, and accurate measurements of
temperature they allow to determine Gibbs excess masses
with relative uncertainties which normally is one order of