Pfeiffer Vacuum

1.2.4 Thermal molecular velocity

Gas molecules in a vessel move back and forth in different directions and at different speeds. Their velocity distribution corresponds to a bell curve having its peak at the most probable velocity

Formula 1-6:

Probable velocity

The mean thermal velocity is

Formula 1-7:

Mean velocity

The following table shows values for selected gases.

Table 1.4: Molar masses and mean thermal velocities of various gases

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