Carbon acentric factor

The carbon di oxi de/lemon oil P-x behavior shown in Figures 4, 5, and 6 is typical of binary carbon dioxide hydrocarbon systems, such as those containing heptane (Im and Kurata, VO, decane (Kulkarni et al., 1 2), or benzene (Gupta et al., 1 3). Our lemon oil samples contained in excess of 64 mole % limonene so we modeled our data as a reduced binary of limonene and carbon dioxide. The Peng-Robinson (6) equation was used, with critical temperatures, critical pressures, and acentric factors obtained from Daubert and Danner (J 4), and Reid et al. (J 5). For carbon dioxide, u> - 0.225 for limonene, u - 0.327, Tc = 656.4 K, Pc = 2.75 MPa. It was necessary to vary the interaction parameter with temperature in order to correlate the data satisfactorily. The values of d 1 2 are 0.1135 at 303 K, 0.1129 at 308 K, and 0.1013 at 313 K. Comparisons of calculated and experimental results are given in Figures 4, 5, and 6. 

If the departure from equation (35) is not too large, it can be treated as a perturbation. The effect of non-central interactions on the second virial coefficient is second order and it is very difficult to distinguish between any of the non-central interactions on the basis of the behaviour of In essence, it is possible to fit the properties of many pure substances to equations based on simple corresponding states and additional terms whose magnitude is proportional to a perturbation parameter that is a measure of the deviation from central forces. One such perturbation parameter is Pitzer s acentric factor. 74,76 another is Rowlinson s In a homologous series the number of carbon atoms in the chain constitutes yet another measure of the perturbation. It can be shown that there is a simple relation between the different factors. ... 

It will be seen from the table that there are considerable differences between the values. Opfell tried to eliminate this problem by expressing the constants in the form of linear functions of an acentric factor. For non-branched aliphatic hydrocarbons and isohydrocarbons, Canjar and Griskey proposed empirical relationships between the values of the constants and critical temperature, as well as the number of carbon atoms in the molecule. 

The acentric factor of the homomorph is defined as the acentric factor of the hydrocarbon molecule, which is obtained by replacing all functional groups of the target molecule with carbon atoms (including any noncarbon atoms in the main structure). This parameter is used in some estimation methods. 

The data bank on basic physical and chemical properties of individual substances stores the following data the name of the substance, molecular mass, the structural formula of the molecule and the number of carbon atoms, melting and boiling temperatures at atmospheric pressure, critical parameters, acentric factor and polarity, parameters of the Lennard-Jones and Stockmayer potentials, the coefficients of an equation for calculation of isobaric heat capacity in the ideal-gas state and some other properties. The content of the bank is enlarged continuously by input of information on new substances. 

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