Sodium superoxide

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Sodium superoxide
IUPAC name
sodium(I) superoxide
Other names
sodium superoxide
12034-12-7 YesY
Jmol 3D model Interactive image
PubChem 61542
RTECS number WE2860010
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
Basicity (pKb) N/A
72.1 J/mol K
115.9 J/mol K
-260.2 kJ/mol
-218.4 kJ/mol
Vapor pressure {{{value}}}
Related compounds
Other anions
sodium oxide
sodium peroxide
Other cations
potassium 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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Infobox references

Sodium superoxide is the inorganic compound with the formula NaO2. This yellow-orange solid is a salt of the superoxide anion. It is an intermediate in the oxidation of sodium by oxygen.


NaO2 is prepared by treating sodium peroxide with oxygen at high pressures:[1]

Na2O2 + O2 → 2 NaO2

It can also be prepared by careful oxygenation of a solution of sodium in ammonia:

Na(in NH3) + O2 → NaO2


The product is paramagnetic, as expected for a salt of the O
anion. It hydrolyses readily to give a mixture of sodium hydroxide, oxygen and hydrogen peroxide.[2] It crystallizes in the NaCl motif.[citation needed]


  1. Stephen E. Stephanou, Edgar J. Seyb Jr., Jacob Kleinberg "Sodium Superoxide" Inorganic Syntheses 1953; Vol. 4, 82-85.
  2. Sasol Encyclopaedia of Science and Technology , G.C. Gerrans, P. Hartmann-Petersen , p.243 "sodium oxides" , google books link