Ethane physical constants

We have now laid the foundation for considering the other hydrocarbons which are similar to methane and ethane and for understanding an interesting relationship which makes of them a familyor series. At the present time about fifty hydrocarbons are known which resemble methane and ethane in being saturated stable, inactive compounds, and to which the name paraffin strictly applies. Some of these hydrocarbons with their empirical formulas and a few of their physical constants are given in the following table ... 

As regards ergotoxine, the analytical results and the physical constants found by Smith and Timmis for their crystalline ergotoxine are in close agreement with those recorded by Stoll and Hofmann for their ergocornine, and Foster has shown that the analytical data for ergotoxine ethane-sulphonate, prepared from ergotoxine purified by Stoll and Hofmann s method, differed but little froiii those prescribed by the British Pharmacopoeia, e.g., specific rotation -f-124° as compared with the official requirement of [aJo 4- 119-122°. 

Figure 1 shows the representation of the experimental isotherm (B. G. Aristov, V. Bosacek, A. V. Kiselev, Trans. Faraday Soc. 1967 63, 2057) of xenon adsorption on partly decationized zeolite LiX-1 (the composition of this zeolite is given on p. 185) with the aid of the virial equation in the exponential form with a different number of coefficients in the series i = 1 (Henry constant), i = 2 (second virial coefficient of adsorbate in the adsorbent molecular field), i = 3, and i = 4 (coefficients determined at fixed values of the first and the second coefficients which are found by the method indicated for the adsorption of ethane, see Figure 4 on p. 41). In this case, the isotherm has an inflection point. The figure shows the role of each of these four constants in the description of this isotherm (as was also shown on Figure 3a, p. 41, for the adsorption of ethane on the same zeolite sample). The first two of these constants—Henry constant (the first virial constant) and second virial coefficient of adsorbate-adsorbate interaction in the field of the adsorbent —have definite physical meanings. 

Deuteroethane distributions have been interpreted in terms of a parameter P, which is the quotient of the rate constants for ethyl to ethene and ethyl reverting to ethane. For molybdenum, tantalum, rhodium and palladium films, a single value of P (respectively 0.25, 0.25, 18 and 28) sufficed to reproduce the observed distribution, assuming that a further deuterium atom is acquired at every opportunity. With other metals, however, two simultaneous values of P appeared to operate, one contributing 30 to 50% of the reaction having a high P value (13.5-18) and another having a much lower P value (0.36-2). This analysis has not however been accorded an interpretation in terms of the metals physical properties or of ensemble sizes and structures responsible for each participant. 

The K constant is usually taken as 1.75, as this value reproduces the rotational barrier in ethane. An essentially identical approach has been used for periodic systems within the physics community, where it is here known as the tight binding model. Recent work in this area has used an approach to parameterize against density functional results, thereby providing a computationally very efficient model capable of yielding fairly accurate results. ... 

Blom, C. E., Altona, C. (1976). Application of self-consistent-field ab initio calculations to organic molecules II. Scale factor method for the calculation of vibrational frequencies from ab initio force constants Ethane, propane and cyclopropane. Molecular Physics, 31,1377. 

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