Sodium superoxide
Appearance
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Names | |
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IUPAC name
sodium superoxide
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Other names
sodium superoxide
sodium dioxide | |
Identifiers | |
3D model (JSmol)
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ChemSpider | |
PubChem CID
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RTECS number |
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UNII | |
UN number | 2547 |
CompTox Dashboard (EPA)
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Properties | |
NaO2 | |
Molar mass | 54.9886 g/mol |
Appearance | Yellow to orange crystalline solid |
Density | 2.2 g/cm3 |
Melting point | 551.7 °C (1,025.1 °F; 824.9 K) |
Boiling point | Decomposes |
Decomposes | |
Basicity (pKb) | N/A |
Structure | |
cubic | |
Thermochemistry | |
Heat capacity (C)
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72.1 J/mol K |
Std molar
entropy (S⦵298) |
115.9 J/mol K |
Std enthalpy of
formation (ΔfH⦵298) |
-260.2 kJ/mol |
Gibbs free energy (ΔfG⦵)
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-218.4 kJ/mol |
Hazards | |
GHS labelling: | |
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Danger | |
H271, H314 | |
P210, P220, P260, P280, P303+P361+P353, P305+P351+P338 | |
NFPA 704 (fire diamond) | |
Flash point | Non flammable |
Related compounds | |
Other anions
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sodium oxide sodium peroxide |
Other cations
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Lithium superoxide Potassium superoxide Rubidium superoxide Caesium superoxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sodium superoxide is the inorganic compound with the formula NaO2.[1] This yellow-orange solid is a salt of the superoxide anion. It is an intermediate in the oxidation of sodium by oxygen.
Preparation
[edit]NaO2 is prepared by treating sodium peroxide with oxygen at high pressures:[2]
- Na2O2 + O2 → 2 NaO2
It can also be prepared by careful oxygenation of a solution of sodium in ammonia:
- Na(in NH3) + O2 → NaO2
It is also produced, along with sodium peroxide, when sodium is stored under inappropriate conditions (e.g. in dirty or partially halogenated solvents)[citation needed].
Properties
[edit]The product is paramagnetic, as expected for a salt of the O−
2 anion. It hydrolyses readily to give a mixture of sodium hydroxide, oxygen and hydrogen peroxide.[3] It crystallizes in the NaCl motif.
References
[edit]- ^ Hayyan, Maan; Hashim, Mohd Ali; AlNashef, Inas M. (2016-02-15). "Superoxide Ion: Generation and Chemical Implications". Chemical Reviews. 116 (5). American Chemical Society (ACS): 3029–3085. doi:10.1021/acs.chemrev.5b00407. ISSN 0009-2665. PMID 26875845.
- ^ Stephen E. Stephanou, Edgar J. Seyb Jr., Jacob Kleinberg "Sodium Superoxide" Inorganic Syntheses 1953; Vol. 4, 82-85.
- ^ Sasol Encyclopaedia of Science and Technology , G.C. Gerrans, P. Hartmann-Petersen , p.243 "sodium oxides" , google books link