Page 137 - Gas Adsorption Equilibria
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3. Gravimetry 123
are: …length of the two beams of the balance, ... mass of adsorbate;
... volume of sorbent / sorbate system and ballast or tare, g ... gravity
of earth, and ... density of sorptive gas.
Figure 3.3. Schematics of a two beam balance with electromagnetic compensation
(Th. Gast, Sartorius) loaded with a sorbent sample of mass and a ballast or tare
of mass
In order to calculate the mass adsorbed from the momentum balance
(3.1) three additional measurements are necessary:
(1) Calibration measurement of the empty balance, i. e. the balance without a
sorbent sample and a ballast or tare, in vacuum In this case we have :
Hence equation (3.1) reduces to
(2) Measurement of the loaded balance in vacuum Since eq.
(3.1) reads
(3) Measurement of the empty balance in the sorptive gas to determine
the moment of the buoyancy forces of the balance parts, i. e. beams, wires,
baskets etc. From (3.1) we get for
