The theoretical basis of the Knudsen effusion method for the measurement of vapour pressures is considered, and the complications inherent in real Knudsen cells and samples are discussed. The thermogravimetric effusion technique and procedure used to determine the"vapour pressures of zirconium tetrachloride with six effusion orifices of different size are described. The results show a strong dependency of measured pressure on orifice size, such that the pressure increases with decreasing orifice area. The Motzfeldt's relationship between equilibrium and steady-state pressures was employed to obtain equilibrium vaporization characteristics of ZrC14• The derived equilibrium pressures fall close to the values obtained from previous static measurements. The sublimation pressures of tin dichloride and tin dibromide were studied in an identical manner, with four and three different orifice sizes, respectively. No systematic variation of measured pressure with orifice size was noted. Self-consistent heats of Sublimation from the data for each orifice were obtained for both.dihalides. An argument is presented whereby the evident vaporization behaviour of the compounds studied can be related to their structural types.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:601119 |
| Date | January 1972 |
| Creators | Abdalla, Osama Abdelhameed |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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