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Dinitrogen trioxide
From Wikipedia, the free encyclopedia
| Dinitrogen trioxide | |
|---|---|
  |
|
| General | |
| Molecular formula | N2O3 |
| Molar mass | 76.01 g/mol |
| Appearance | blue liquid |
| CAS number | 10544-73-7 |
| Properties | |
| Density and phase | 1.4 × 103 kg m−3, liquid |
| Solubility in water | reacts |
| Melting point | −100.1°C (173.05 K) |
| Boiling point | 3°C (276 K) |
| Structure | |
| Thermodynamic data | |
| Std enthalpy of formation ΔfH |
+91.20 kJ/mol |
| Standard molar entropy S |
314.63 J·K−1·mol−1 |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Highly toxic (T+) |
| NFPA 704 |
0
3
0
OX
|
| R-phrases | R26, R34 |
| S-phrases | S1/2, S9, S26, S28, S36/37/39, S45 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related nitrogen oxides | N2O NO NO2 N2O4 N2O5 |
| Related compounds | Nitric acid Nitrous acid |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
The chemical compound dinitrogen trioxide (N2O3) is a pale blue liquid from the group of nitrogen oxides.
Contents |
Dinitrogen trioxide is produced by mixing equal parts of nitric oxide (NO) and nitrogen dioxide (NO2), and cooling the mixture below −21°C (−6°F). The gases react, forming the blue liquid N2O3. Dinitrogen trioxide is only stable in the liquid and solid phases, and decomposes back to NO and NO2 when heated above 3°C.
Dinitrogen trioxide has an unusually long N−N bond at 186 pm. While N−N bonds are more often similar to that in hydrazine (145 pm), some other oxides of nitrogen do possess long N−N bonds, including dinitrogen tetroxide (175 pm). The N2O3 molecule is planar and exhibits Cs symmetry. The dimensions displayed below come from microwave spectroscopy of low-temperature, gaseous N2O3:
It is the anhydride of the unstable nitrous acid (HNO2), and produces it when mixed into water. If the nitrous acid is not then used up quickly, it decomposes into nitric oxide and nitric acid. Nitrite salts are sometimes produced by adding N2O3 to solutions of bases.