Dinitrogen pentoxide
Chemical compound / From Wikipedia, the free encyclopedia
Dinitrogen pentoxide (also known as nitrogen pentoxide or nitric anhydride) is the chemical compound with the formula N2O5. It is one of the binary nitrogen oxides, a family of compounds that only contain nitrogen and oxygen. It exists as colourless crystals that sublime slightly above room temperature, yielding a colorless gas.[4]
Names | |
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IUPAC name
Dinitrogen pentoxide | |
Other names
Nitric anhydride Nitronium nitrate Nitryl nitrate DNPO Anhydrous nitric acid | |
Identifiers | |
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ChemSpider |
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ECHA InfoCard | 100.030.227 |
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PubChem CID |
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Properties | |
N2O5 | |
Molar mass | 108.01 g/mol |
Appearance | white solid |
Density | 2.0 g/cm3[1] |
Boiling point | 33 °C (91 °F; 306 K) sublimes[1] |
reacts to give HNO3 | |
Solubility | soluble in chloroform negligible in CCl4 |
−35.6×10−6 cm3 mol−1 (aq) | |
1.39 D | |
Structure[2] | |
Hexagonal, hP14 | |
P63/mmc No. 194 | |
a = 0.54019 nm, c = 0.65268 nm | |
Formula units (Z) |
2 |
planar, C2v (approx. D2h) N–O–N ≈ 180° | |
Thermochemistry[3] | |
Heat capacity (C) |
143.1 J K−1 mol−1 (s) 95.3 J K−1 mol−1 (g) |
Std molar entropy (S⦵298) |
178.2 J K−1 mol−1 (s) 355.7 J K−1 mol−1 (g) |
Std enthalpy of formation (ΔfH⦵298) |
−43.1 kJ/mol (s) +13.3 kJ/mol (g) |
Gibbs free energy (ΔfG⦵) |
113.9 kJ/mol (s) +117.1 kJ/mol (g) |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards |
strong oxidizer, forms strong acid in contact with water |
NFPA 704 (fire diamond) | |
Flash point | Non-flammable |
Related compounds | |
Nitrous oxide Nitric oxide Dinitrogen trioxide Nitrogen dioxide Dinitrogen tetroxide | |
Related compounds |
Nitric acid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dinitrogen pentoxide is an unstable and potentially dangerous oxidizer that once was used as a reagent when dissolved in chloroform for nitrations but has largely been superseded by nitronium tetrafluoroborate (NO2BF4).
N2O5 is a rare example of a compound that adopts two structures depending on the conditions. The solid is a salt, nitronium nitrate, consisting of separate nitronium cations [NO2]+ and nitrate anions [NO3]−; but in the gas phase and under some other conditions it is a covalently-bound molecule.[5]