Researches on heat of combustion IV: Technique for the determination of the heats of combustion of volatile liquids

Abstract

A method is described for filling thin‐walled ampullae with volatile liquids with the total exclusion of air and water. In this way it is possible to weigh out accurately the amount of material used for a heat of combustion measurement before the experiment is made. To aid the combustion reaction in proceeding to completion a high platinum crucible is used covered with a platinum shield. In a normal heat of combustion reaction it is impossible to detect the presence of carbon monoxide in the combustion gases. The reproducibility obtained is 0.01‐0.02%.

Thermochemical Properties of Triphenylalkanes and Tetraphenylmethane. Strain in Phenyl Substituted Alkanes

“…The standard enthalpies of formation ∆ f H m °(cr) of compounds A-C and E have been determinated by Coops et al (1947Coops et al ( , 1953 using combustion calorimetry. Two compounds measured by this group have been remeasured by Beckhaus et al (1990), and their new results were in acceptable agreement with those from Coops.…”

“…Two compounds measured by this group have been remeasured by Beckhaus et al (1990), and their new results were in acceptable agreement with those from Coops. Therefore the values ∆ f H m °(cr) from Coops et al (1947Coops et al ( , 1953 were taken into account for the calculation of the gaseous standard enthalpies of formation ∆ f H m °(g) of these compounds (Table 5).…”

“…d Taken from Coops et al (1953). e Taken from Coops et al (1947). a Estimated as a sum of strain-free increments for alkanes (Schleyer et al, 1970) b Estimated: HS ) (∆fHm°(g) -∑(strain-free increments)); the uncertainties of the HS values were suggested to be only equal to those of the experimental ∆fHm°(g) of phenylalkanes.…”

“…But only a very few reliable thermochemical quantities of geminal phenyl substituted alkanes are known from the literature (Pedley et al, 1986). The series of polyphenyl substituted alkanes has been studied by Coops et al (1947Coops et al ( , 1953, using combustion calorimetry, but the absence of the systematical investigation on enthalpies of sublimation for these compounds thwarted the interpretation of their thermochemical properties in the gaseous phase. Beckhaus et al (1990) measured some tetraphenyl substituted compounds.…”