3

My teacher gave the explanation stating that consider that first the nitrogen in lower state is oxidised to $\ce{N2}$ and then the further oxidation would stop as the $\ce{N-N}$ bond energy of $\ce{N2}$ is very high and can't be overcome under normal conditions.

But my doubt is can't the nascent nitrogen (formed during the formation of $\ce{N2})$ react further with $\ce{O2}$ and get oxidised to some higher oxides like $\ce{NO2}$ or $\ce{N2O}?$

The Latimer diagram shows that it is possible for oxygen to oxidise the nitrogen to higher states:

Latimer diagram Of nitrogen

andselisk
  • 37,604
  • 14
  • 131
  • 217
Govind
  • 318
  • 1
  • 10
  • 1
    I don't think they do. If you search "combustion products of triethylamine" for example you will find phrases such as "Combustion products include: carbon dioxide (CO2), nitrogen oxides (NOx), other pyrolysis products typical of burning organic material." – Waylander Jan 26 '21 at 08:53
  • 1
    Additionally, NOx is created during gas engine combustion from aerial N2, as equilibrium N2 + O2 <=> 2 NO is not so strongly shifted to the left at high temperatures. – Poutnik Jan 26 '21 at 09:13
  • 1
    Side note: "nascent nitrogen" is an obsolete term used to explain high reactivity in certain cases long time ago. These days, it's more appropriate to call it by what it really is: atomic nitrogen. – andselisk Jan 26 '21 at 09:13
  • 1
    What else could it be? All nitrogen oxides are endothermic. I mean, yeah, they would form to some tiny extent, but not as the major product. – Ivan Neretin Jan 26 '21 at 09:50
  • @govind Note that atomic nitrogen would help with kinetics. But it must fight the thermodynamics in the first place. Molecular nitrogen is thermodynamically highly preferred, forming nitrogen oxides just as minor compounds. – Poutnik Jan 26 '21 at 09:54
  • @Poutnik The electrode potential for conversion of NH4+ to N2O4 and NO to N2O4 according to the Latimer diagram are -0.89V and -1.033V. Also the conversion of NO to NO2 is spontaneous in atmospheric oxygen. so thermodynamics might not be the appropriate reason for molecular nitrogen being the major product. – Govind Jan 26 '21 at 10:56
  • is there something special for this rxn https://www.sciencedirect.com/science/article/abs/pii/0021961483901271 – Govind Jan 26 '21 at 10:57
  • 1
    What is important is the standard electrode potential, or the equivalent standard reaction Gibbs energy for conversions of particular nitrogen species to $\ce{N2}$. Like jumping from a tree branch to another branch can produce energy, but molecular nitrogen is on the ground. – Poutnik Jan 26 '21 at 10:59
  • @andselisk Converted my (deleted) comment into a question: Why is the term “nascent nitrogen” still used in metallurgical industries? – Nilay Ghosh Aug 04 '21 at 10:40
  • @Govind not only do they give elemental nitrogen, they do give all sorts of nitrogen oxides. See these papers for more info.: https://pubs.rsc.org/En/content/articlelanding/1947/an/an9477200142/unauth... https://www.sciencedirect.com/science/article/abs/pii/S0926860X02000133 ... https://www.sciencedirect.com/science/article/abs/pii/0026265X66900531 – Nilay Ghosh Aug 05 '21 at 02:37

0 Answers0