The Dissociation Constant of Molecular Nitrogen: An Out-of-Date Value Inorganic chemistry textbooks use, in some cases, the data of Kzss for the dissociation equilibrium of Nz as asupport of the stability for the nitrogen-nitrogen bond in the diatomic molecule or as interesting datum among the molecular properties. The often mentioned value of Kzs8 in these texts may possibly have its origin in the paper of Giauque and Clayton' and must be considered inadequate because the authors clearly pointed out that their results, as far as the dissociation of nitrogen is concerned, were "provisional calculations of the dissociation constant." The provisionality was determined hy the value used (182,OW cal) for the dissociation energy of the molecule at OK ' (E'o) that was considered only an approximate value. The value now accepted for Eooof the nitrogen molecule is much higher than the mentioned value: 225,100 50 eal2. According to this and to the paperslJ we can obtain KZg8= 2 X 10-160, a very different value from that mentioned in the = I X 10"and Kzo,rn= 1.29 X lo5.More information on K values usual literature. On the same basis, we can calculate Gpw at other temneratures is available uoon reauest. Giauque, W. F., and Clayton, J. O., J. Arner. Chem. Soc., 55,4815 (1933). De Maria, G., and Balcucci, G., "MTP, Physical Chemistry Series One," Val. 10, (Editor: Skinner, H.A,) Butteworth, London, 1972, p. 211. Dbring, W., 2.Elektroehern., 53,106 (1949) Universidad d e Santiago de Compostela J. S. Casas M. R. Bermejo Spain J. Sordo M. Garoso
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Volume 55, Number 10. October 1978 1 679
