Nitrogen, dissociation energy

It is estimated that each year approximately 150 million tonnes of nitrogen are fixed biologically compared to 120 million tonnes fixed industrially by the Haber process (p. 421). In both cases N2 is converted to NH3, requiring the rupture of the N=N triple bond which has the highest dissociation energy (945.41 kJmol )... 

FIGURE 2.16 The bond dissociation energies, in kilojoules per mole of nitrogen, oxygen, and fluorine molecules. Note how the bonds weaken in the change from a triple bond in N, to a single bond in F,... 

Figure 7.19. (Left-hand side) Comparison between experimental sticking coefficients of N2 on Fe(l 11) and the prediction on the basis of Eq. (57) with an activation energy of 0.03 eV. (Right-hand side) Potential energy diagram for molecular nitrogen dissociating on Fe(l 11).

Fig. 9 Deprotonation of cations radicals of synthetic analogs of NADH by oxygen or nitrogen bases in acetonitrile. Correlation between the intrinsic barrier and the homolytic bond dissociation energy of the cation radical (AH + —> A+ + H ).

It has been proposed that this reaction intermediate could decompose to produce HCN and CH3 [55], Chemiluminescence from alkanes can be greatly enhanced by addition of HC1. The proposed explanation is that energy transfer from active nitrogen dissociates HC1 to produce chlorine atoms, which have rapid hydrogen-atom abstraction reactions with alkanes,... 

Table 2. Bond dissociation energies of alkenes, alkynes, and aromatics Table 3. Bond dissociation energies of C/H/O compounds Table 4. Bond dissociation energies of sulfur-containing compounds Table 5. Bond dissociation energies of nitrogen-containing compounds Table 6. Bond dissociation of halocarbons...

TABLE D5 Bond Dissociation Energies of Nitrogen-Containing Compounds... 

Nitrogen. Molecular nitrogen N2 has a dissociation energy of 950 kJ/mol, and the N-N triple bond is one of the strongest known chemical bond. Shock-wave experiments disclosed the possibility of N-N dissociation in condensed phases [224, 319-322]. From this an interest arose in the possible obtainment of arrays of N-N single bonds that could form in potentially energetic materials. Ab initio calculations of various kinds [323-327] showed that actually at high pressure... 

Carbon Monoxide. There are close similarities between carbon monoxide and nitrogen. The molecules are isoelectronic, and the bond lengths and dissociation energies are quite comparable. The phase diagrams of the two compounds show the same trends in the moderate pressure range with a variety of phase transitions between essentially alike crystal structures [333], when allowance is made for the lack of the inversion center and the presence of a weak electric dipole moment in carbon monoxide. However, the behavior and stability at higher... 

The (at least approximate) validity of Eqs. (6.12)-(6.14) is clearly demonstrated by the remarkable quality of intrinsic CN bond energies and of bond dissociation energies calculated by means of nitrogen net atomic charges deduced in this manner. 

Straightforward applications of the theory are presented in the atom-by-atom approach, as exemplified in Table 15.4, using charges deduced from NMR shifts, Eq. (6.8) for the carbon atoms, and Eqs. (6.12)-(6.14) for the nitrogen atoms. (CN bond dissociation energies and comparisons with the corresponding intrinsic bond energies are described in Chapter 12 for both alkylamines and selected nitroalkanes.)... 

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