Potassium superoxide
| Potassium superoxide | ||
|---|---|---|
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| IUPAC name Potassium dioxide | ||
| Other names Potassium superoxide | ||
| Identifiers | ||
| CAS number | 12030-88-5  | |
| PubChem | 61541 | |
| RTECS number | TT6053000 | |
| Jmol-3D images | {{#if:O=O.[K+]|Image 1 | |
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| Properties | ||
| Molecular formula | KO2 | |
| Molar mass | 71.10 g mol−1 | |
| Appearance | yellow solid | |
| Density | 2.14 g/cm3, solid | |
| Melting point | 560 °C; 1,040 °F; 833 K (decomp.) | |
| Solubility in water | decomposes | |
| Structure | ||
| Crystal structure | Body-centered cubic (O2−) | |
| Thermochemistry | ||
| Std enthalpy of formation ΔfH |
−283 kJ·mol−1[1] | |
| Standard molar entropy S |
117 J·mol−1·K−1[1] | |
| Hazards | ||
| R-phrases | 8-14-34 | |
| S-phrases | 17-27-36/37/39 | |
| Main hazards | corrosive, oxidant | |
| NFPA 704 |
 0
3
3
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| Related compounds | ||
| Other anions | Potassium oxide Potassium peroxide | |
| Other cations | Sodium superoxide | |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | ||
| Infobox references | ||
Potassium superoxide is the inorganic compound with the formula KO2. It is a yellow solid that decomposes in moist air. It is a rare example of a stable salt of the superoxide ion. Potassium superoxide is used as an oxidizing agent in industrial chemistry, as a CO2 scrubber, H2O dehumidifier and O2 generator in rebreathers, spacecraft, submarines and spacesuit life support systems.
Production and reactions
Potassium superoxide is produced by burning molten potassium in an atmosphere of oxygen.[2]
- K + O2 → KO2
Important reactions:
- 4 KO2 + 2 H2O → 4 KOH + 3 O2
- 4 KOH + 2 CO2 → 2 K2CO3 + 2 H2O
- Combine two first reaction:
- 4 KO2 + 2 CO2 → 2 K2CO3 + 3 O2
If more water and CO2 available:
- 2 K2CO3 + 2 CO2 + 2 H2O → 4 KHCO3
- Overall Reaction:
- 4 KO2 + 4 CO2 + 2 H2O → 4 KHCO3 + 3 O2
Applications
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 its dangerously explosive reaction with water. The theoretical capacity of KO2 is the absorption of 0.618 kg CO2 per kg of absorbent while 0.380 kg O2 are generated per kg of absorbent. For one KO2 molecule, it's one CO2 molecule but only 0.75 oxygen molecules. The human body though will produce less CO2 molecules than oxygen molecules needed because oxidation of food also needs oxygen to produce water and urea.
References
- ↑ 1.0 1.1 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 0-618-94690-X.
- ↑ Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort “Peroxo Compounds, Inorganic” Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_177.pub2
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