Potential binaries, first ionization

Equation 11 was much less satisfactory, even when the coefficient was adjusted to minimize the deviation. The optimum value of the coefficient was 0.18, in agreement with Lin s conclusion for rare-gas mixtures, but the root-mean-square deviation of k j was 0.08. Any relationship involving I, the first ionization potential, is doomed to failure when applied to heavy hydrocarbon mixtures because I, for a given homologous series, is very weakly dependent on carbon number. For example, the I of n-decane is 10.19 eV, only 0.24 eV less than that of n-hexane, while that of n-eicosane should be about 10.04 eV. Thus, a correlation of kijs for methane-paraffin binaries based solely on ionization potentials would give the same result for all Ci0+ paraffins. 

The first ionization potential may prove useful in sorting out and ordering the data for binaries of inorganic compounds, but it is certainly of little use in the prediction of ky s for hydrocarbon-hydrocarbon binaries. For example, the I of n-pentane (10.55 eV) is very similar to that of ethylene (10.51 eV), but the kys for the n-pentane binaries are markedly lower than those for the corresponding ethylene binaries (4). On the other hand, the ethylene and ethane binaries have similar kys (Figure 2), even though the I of ethane is 1.25 eV higher than for ethylene (20). 

Argon (Ar) gas, for example, is over 30 times more abundant than carbon dioxide and, therefore, not rare. And xenon is not inert it s first compounds were created in 1962. When xenon (Xe) forms binary fluorides and oxides as well as fluoride complexes and oxoanions, the stability of these compounds is very low. It s reactivity is related to increasing atomic size as you go down the table, which leads to a decrease in the first ionization potentials. Xenon tetraflouride (XeF,) is made by mixing one part xenon gas to three parts fluorine gas in a container at 400 °C. Compounds have been confirmed for argon (HArF), krypton (KrF2), xenon (numerous fluorides, oxyfluorides, and oxides), and radon (RnF2). It s believed that compounds exist with helium and neon as well, though none have been experimentally proven to date. 

---