Sulphur physical constants

That the reaction with concentrated sulphuric acid may be regarded an excellent expedient to recognise different kinds from irregular rmbebs, for all kinds colouring yellow with H.SO4 also show important irregularities of the physical constants of the oil. 

Physical Properties.—Sulphuryl chloride is a colourless, fuming liquid, with an extremely pungent odour. Z)2 = 1-6074 ->t " = l-4437. It boils at 69-1° C. at 760 mm. pressure, and freezes at —46° C.5 The vapour density is normal at first, but when the chloride is kept, even at 100° C., its vapour commences to dissociate into sulphur dioxide and chlorine. At 200° C. dissociation is almost complete.6 When dissolved in benzene the substance shows a molecular- weight corresponding with S02C12. At ordinary temperatures the specific heat is 0-233, the latent heat of evaporation 32-4 calories per gram, and the heat of formation from the elements approximately 89,540 calories per gram-molecule.7 The dielectric constant at 20° C. is 8-5. As a solvent, the ebullioscopic constant of sulphuryl chloride has been found to have... 

Van t Hoff then deals with chemical equilibrium on the basis of the law of mass action, and the change of equilibrium constant with temperature, introducing the case of condensed systems in the absence of vapour and a transition point (point de transition). Physical equilibria are special cases of chemical equilibria. Graphical methods with vapour pressure curves (e.g. for the allotropic forms of sulphur) are introduced. The principle of mobile equilibrium is explained for homogeneous and heterogeneous equilibria, and the Thomsen-Berthelot principle criticised (see pp. 614, 620). The last chapter, on affinity ,gives the definition The work of affinity (A) is equal to the heat produced in the transformation (q), divided by the absolute temperature of the transition point (P) and multiplied by the difference between this and the given temperature (P) ... 

In Lavoisier s work on the analysis of mineral waters eight different mixtures of alcohol and water were used to separate the salts formed on evaporation, a method used by Macquer (see p. 87). The results are of no interest. Lavoisier then believed there were only two mineral acids, sulphuric and hydrochloric the nature of nitric acid is unknown and the idea (Sage s) that phosphoric acid is a peculiar acid is not sufficiently demonstrated. Several other articles by Lavoisier on the analyses of natural waters mention the statement by Le Roy that earth can pass over with water on distillation, and Lavoisier believed that true salts would volatilise with water more readily than earth. He described determinations of density by a hydrometer (areometre) and unsuccessful attempts to calculate the composition of solutions from the density. The composition was correctly related to the nature of the strata of the earth through which the waters had passed. A constant-immersion hydrometer is fully described in an article on the determination of specific gravity. Lavoisier had some idea that purely physical methods might replace chemical analysis of waters, and as Thomson said, chemical analyses were not the investigations in which Lavoisier excelled . 

Other Physical Properties.—Conformational information for thiols and sulphides can be obtained from enthalpy of formation data. Proton-transfer of benzyl-mercaptan (protonation at sulphur with CF3SO3H, and de-protonation by imidazole) has been studied. Thermodynamic parameters for acidity constants of substituted benzenethiols, and for hydrogen-bonding interactions between alkanols and di-n-octyl sulphide and the analogous ether and N-methylamine, reveal a dominant electronic influence of the orM<>-substituent, and substantially higher hydrogen-bond acceptor ability for the aliphatic sulphide than is generally assumed. ... 

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