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2004
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Chemical Education Today
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Letters
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Boiling Point versus Mass
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Michael Laing
School of Pure and Applied Chemistry, University of Natal, Durban 4041, South Africa
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May 2004
Vol. 81 No. 5
p. 642
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| Full Text |
The author's reply to Rich:
I am very pleased that Ronald Rich has written making these comments, because he is pre-eminent in this field, beginning with his early book, Periodic Correlations (1). He rightly emphasizes two important points: 1. The attractive forces within a liquid are not gravitational in nature. 2. It is the polarizability of the electron clouds of the surfaces of the outermost atoms that dominates the attractive London forces. The following series of ÒsimpleÓ tetrahedral tetrachlorides shows that boiling point is not directly related to molecular mass nor is it related in a simple way to the sum of polarizabilities of the outermost atoms, which is identical throughout this series. Similarly, the following series of methane derivatives poses worse problems. The molar refraction decreases regularly from CH4 to CF4, clearly not giving a good measure of the boiling point. It appears that now the dipole moment is somehow involved. If these two series of simple tetrahedral molecules pose problems, it must be evident that the situation is indeed complex. For me, this is a case of: ÒThere are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.Ó
Literature Cited
- Rich, R. Periodic Correlations; Benjamin: New York, 1965.
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| More Information |
 Citation |
Laing, Michael. J. Chem. Educ. 2004 81 642.
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Keywords |
Atomic Properties / Structure; Bromine; Chlorine; Fluorine; Intermolecular Forces; Liquids; Molecular Properties / Structure
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History |
Created:
Last Updated: |
April 1, 2004
February 18, 2005
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