Potassium superoxide

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Potassium superoxide
IUPAC name	Potassium dioxide
Other names	Potassium superoxide
Identifiers
CAS number	[12030-88-5]
Properties
Molecular formula	KO2
Molar mass	71.10 g/mol
Appearance	yellow solid
Density	2.14 g/cm3, solid
Melting point	425 °C decomp.
Solubility in water	Decomposes
Hazards
Main hazards	corrosive, oxidant
R-phrases	8-14-34
S-phrases	17-27-36/37/39
Related compounds
Other anions	Potassium oxide Potassium peroxide
Other cations	Sodium superoxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Potassium superoxide is the chemical compound with the formula KO₂. This rare salt of the superoxide ion is produced by burning molten potassium in pure oxygen. Potassium superoxide is used as an oxidizing agent in industrial chemistry, as a CO₂ scrubber, H₂O dehumidifier and O₂ generator in rebreathers, spacecraft and spacesuit life support systems.

Important reactions:

4 KO₂ + 2 H₂O → 4 KOH + 3 O₂

2 KOH + CO₂ → K₂CO₃ + H₂O

K₂CO₃ + CO₂ + H₂O → 2 KHCO₃

The Russian Space Agency has had success using potassium superoxide in chemical oxygen generators for its spacesuits and Soyuz spacecraft. KO₂ has also been utilized in canisters for rebreathers for fire fighting and mine rescue work, but had limited use in scuba rebreathers because of the dangers of explosive reaction with water. The theoretical capacity of KO₂ is the absorption of 0.309 kg CO₂ per kg of absorbent while 0.38 kg O₂ are generated per kg of absorbent. The human body though will produce more CO₂ than oxygen absorbed, thus a device or absorbent specifically for CO₂ scrubbing may also be required.

[edit] Structural trends in dioxygen compounds

The derivatives of dioxygen, O₂, have characteristic O-O distances that correlate with the bond order of the O-O bond.

Dioxygen compound	name	O-O distance in Å	O-O bond order
O2+	dioxygenyl cation	1.12	2.5
O2	dioxygen	1.21	2
O2-	superoxide	1.28	1.5[1]
O22-	peroxide	1.49	1

[edit] References

1. ^ Abrahams, S. C.; Kalnajs, J. “The Crystal Structure of α-Potassium Superoxide” Acta Crystallographica (1955) volume 8, pages 503-506. DOI:10.1107/S0365110X55001540.