CHED 1014 |
| Two experimental values (-19.3 ± 0.3 and –17.8 ± 0.1 kcal/mol) for the heat of formation of nitromethane have been reported. Although these values differ by only 1.5 kcal/mol, substantially greater differences in theoretical and experimental results occur when these differing values are used to calculate thermodynamic properties. This is especially evident when these differing values for the heat of formation of nitromethane are used to calculate thermodynamic properties of polynitro compounds. For example, when density function theory (DFT) is coupled with the use of isodesmic reactions, the heat of formation of octanitrocubane is calculated to be 160.6 or 172.6 kcal/mol, depending on which value is used. It should also be appreciated that several computational theories depend upon having access to reliable experimental data for testing and development. Our results coupled with a comprehensive review of the literature support the lower (-19.3 ± 0.3 kcal/mol) experimental value. This is problematic because the higher value (-17.8 ± 0.1 kcal/mol) has been used in the development and/or testing of several semiempirical models as well as the ab initio Gaussian theory (G1, G2 and G3). |
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Undergraduate Research Poster Session: Physical Chemistry
2:00 PM-4:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster
Division of Chemical Education |