DETERMINATION OF HGCL2 VAPOR-PRESSURE BY THE KNUDSEN CELL METHOD

The mercuric chloride (HgCl2) vapor pressure was measured between 343 and 454 K by the Knudsen cell method at relatively high pressures wher e the flow rate is not purely molecular. Four cells with different ori fice sizes were used. Knudsen equation cannot explain accurately the e xperimental mass loss by using molecular plus hydrodynamical equations . Calculations from our measurements were performed taking into accoun t of an ''effective radius'' for our orifices, and this radius depends on the relative weight of the two contributions. We compare our resul ts with those existing in literature.