Most chemists draw the direction of an electric dipole backwards. This inconsistency in sign convention is more than a trivial oversight or matter of convenience. We are introducing an incorrect convention that is central to our student’s understanding of fundamental thermodynamics; which way is up? As a student matures from general chemistry to organic through analytical, physical, inorganic, and biochemistry they are reintroduced to similar, powerful concepts that hold our discipline together. However, this reconnection of chemical principles comes with each subdiscipline’s own idiosyncrasies and a highly contextual framework. Reexamination of a central concept from the perspective of a new subdiscipline should not introduce misconceptions about that concept. When misconceptions introduced through chemical language can be avoided, we should change the way we speak.
. Can. J. Chem. 66, 562 (1988).The hydrogen bond enthalpies of urea and methyl-substituted ureas with water and DMF have been determined by the pure-base calorimetric method. Transfer enthalpies between water and DMF have been calculated for dilute solutions of the ureas according to a previously developed model. The first solvation sphere of urea in water consists of five water molecules. Solvation spheres are given for other methyl-substituted ureas in water and DMF.
Experimental observations of clusters TeF6 together with molecular dynamics simulations have uncovered some kinetic aspects of phase transitions that can be expected to apply to related systems. It was predicted, accordingly, that under conditions of fast cooling transition-metal hexafluorides could be induced to crystallize into a monoclinic form which had never been observed for the compounds. Electron diffraction studies of large clusters of MoF6 and WF6, generated by condensation of the vapor in supersonic expansions through a Laval nozzle, confirmed the prediction. A rationale for this behavior is advanced.
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