Oxygen difluoride
Names | |
---|---|
IUPAC name Oxygen difluoride | |
Other names
| |
Identifiers | |
CAS Number |
|
3D model (JSmol) |
|
ChEBI |
|
ChemSpider |
|
ECHA InfoCard | 100.029.087 |
EC Number |
|
PubChem CID |
|
RTECS number |
|
UNII |
|
CompTox Dashboard (EPA) |
|
InChI
| |
| |
Properties | |
Chemical formula | OF2 |
Molar mass | 53.9962 g/mol |
Appearance | colorless gas, pale yellow liquid when condensed |
Odor | peculiar, foul |
Density |
|
Melting point | −223.8 °C (−370.8 °F; 49.3 K) |
Boiling point | −144.75 °C (−228.55 °F; 128.40 K) |
Solubility in water | hydrolyzes[1] slowly |
Vapor pressure | 48.9 atm (at −58.0 °C or −72.4 °F or 215.2 K[a]) |
Thermochemistry | |
Heat capacity (C) | 43.3 J/mol K |
Std molar entropy (S⦵298) | 246.98 J/mol K |
Std enthalpy of formation (ΔfH⦵298) | −24.5 kJ mol−1 |
Gibbs free energy (ΔfG⦵) | 42.5 kJ/mol |
Hazards | |
GHS labelling:[4] | |
Danger | |
H270, H280, H314, H330 | |
NFPA 704 (fire diamond) | 4 0 3 OX |
Lethal dose or concentration (LD, LC): | |
LC50 (median concentration) |
|
NIOSH (US health exposure limits): | |
PEL (Permissible) | TWA 0.05 ppm (0.1 mg/m3)[2] |
REL (Recommended) | C 0.05 ppm (0.1 mg/m3)[2] |
IDLH (Immediate danger) | 0.5 ppm[2] |
Related compounds | |
Related compounds |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references |
Oxygen difluoride is a chemical compound with the formula OF2. As predicted by VSEPR theory, the molecule adopts a bent molecular geometry. It is a strong oxidizer and has attracted attention in rocketry for this reason.[5] With a boiling point of −144.75 °C, OF2 is the most volatile (isolable) triatomic compound.[6] The compound is one of many known oxygen fluorides.
Preparation
Oxygen difluoride was first reported in 1929; it was obtained by the electrolysis of molten potassium fluoride and hydrofluoric acid containing small quantities of water.[7][8] The modern preparation entails the reaction of fluorine with a dilute aqueous solution of sodium hydroxide, with sodium fluoride as a side-product:
- 2 F2 + 2 NaOH → OF2 + 2 NaF + H2O
Structure and bonding
It is a covalently bonded molecule with a bent molecular geometry and a F-O-F bond angle of 103 degrees. Its powerful oxidizing properties are suggested by the oxidation number of +2 for the oxygen atom instead of its normal −2.
Reactions
Above 200 °C, OF2 decomposes to oxygen and fluorine by a radical mechanism.
- 2 OF2 → O2 + 2 F2
OF2 reacts with many metals to yield oxides and fluorides. Nonmetals also react: phosphorus reacts with OF2 to form PF5 and POF3; sulfur gives SO2 and SF4; and unusually for a noble gas, xenon reacts (at elevated temperatures) yielding XeF4 and xenon oxyfluorides.
Oxygen difluoride reacts very slowly with water to form hydrofluoric acid:
- OF2 + H2O → 2 HF + O2
It can oxidize sulphur dioxide to sulfur trioxide and elemental fluorine:
- OF2 + SO2 → SO3 + F2
However, in the presence of UV radiation, the products are sulfuryl fluoride (SO2F2) and pyrosulfuryl fluoride (S2O5F2):
- OF2 + 2 SO2 → S2O5F2
Safety
Oxygen difluoride is considered an unsafe gas due to its oxidizing properties. It reacts explosively with water.[9] Hydrofluoric acid produced by the hydrolysis of OF2 with water is highly corrosive and toxic, capable of causing necrosis, leaching calcium from the bones and causing cardiovascular damage, among a host of other highly toxic effects. Other acute poisoning effects include: pulmonary edema, bleeding lungs, headaches, etc. [10]Chronic exposure to oxygen difluoride, like that of other chemicals that release fluoride ions, can lead to fluorosis and other symptoms of chronic fluoride poisoning. Oxygen difluoride may be associated with kidney damage. [10]The maximum workplace exposure limit is 0.05 ppm.[11][10]
Popular culture
In Robert L. Forward's science fiction novel Camelot 30K, oxygen difluoride was used as a biochemical solvent by fictional life forms living in the solar system's Kuiper belt. While OF2 would be a solid at 30 K, the fictional alien lifeforms were described as endothermic, maintaining elevated body temperatures and liquid OF2 blood by radiothermal heating.
Notes
- ^ This is its critical temperature, which is below ordinary room temperature.
References
- ^ "difluorine monoxide; oxygen difluoride, physical properties, suppliers, CAS, MSDS, structure, Molecular Formula, Molecular Weight, Solubility, boiling point, melting point". www.chemyq.com.
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0475". National Institute for Occupational Safety and Health (NIOSH).
- ^ "Oxygen difluoride". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ GHS: GESTIS 570242
- ^ "Oxygen Difluoride - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2023-11-03.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 819. ISBN 978-0-08-037941-8.
- ^ Lebeau, P.; Damiens, A. (1929). "Sur un nouveau mode de préparation du fluorure d'oxygène" [A new method of preparation of oxygen fluoride]. Comptes rendus hebdomadaires des séances de l'Académie des Sciences (in French). 188: 1253–1255. Retrieved February 21, 2013.
- ^ Lebeau, P.; Damiens, A. (1927). "Sur l'existence d'un composé oxygéné du fluor" [The existence of an oxygen compound of fluorine]. Comptes rendus hebdomadaires des séances de l'Académie des Sciences (in French). 185: 652–654. Retrieved February 21, 2013.
- ^ "OXYGEN DIFLUORIDE | CAMEO Chemicals | NOAA". cameochemicals.noaa.gov. Retrieved 2024-05-14.
- ^ a b c www.kdocs.cn https://www.kdocs.cn/singleSign4CST?cb=https%3A%2F%2Fwww.kdocs.cn%2Fl%2Fcn9j8vXb7Gq3%3Ff%3D201&ts=1715699652. Retrieved 2024-05-14.
{{cite web}}
: Missing or empty|title=
(help) - ^ "CDC - NIOSH Pocket Guide to Chemical Hazards - Oxygen difluoride". www.cdc.gov. Retrieved 2024-05-14.
External links
- National Pollutant Inventory - Fluoride and compounds fact sheet
- WebBook page for OF2
- CDC - NIOSH Pocket Guide to Chemical Hazards
- v
- t
- e
HF | ?HeF2 | |||||||||||||||||
LiF | BeF2 | BF BF3 B2F4 +BO3 | CF4 CxFy +CO3 | NF3 FN3 N2F2 NF N2F4 NF2 ?NF5 | OF2 O2F2 OF O3F2 O4F2 ?OF4 | F2 | Ne | |||||||||||
NaF | MgF2 | AlF AlF3 | SiF4 | P2F4 PF3 PF5 | S2F2 SF2 S2F4 SF3 SF4 S2F10 SF6 +SO4 | ClF ClF3 ClF5 | ?ArF2 ?ArF4 | |||||||||||
KF | CaF CaF2 | ScF3 | TiF2 TiF3 TiF4 | VF2 VF3 VF4 VF5 | CrF2 CrF3 CrF4 CrF5 ?CrF6 | MnF2 MnF3 MnF4 ?MnF5 | FeF2 FeF3 FeF4 | CoF2 CoF3 CoF4 | NiF2 NiF3 NiF4 | CuF CuF2 ?CuF3 | ZnF2 | GaF2 GaF3 | GeF2 GeF4 | AsF3 AsF5 | Se2F2 SeF4 SeF6 +SeO3 | BrF BrF3 BrF5 | KrF2 ?KrF4 ?KrF6 | |
RbF | SrF SrF2 | YF3 | ZrF2 ZrF3 ZrF4 | NbF4 NbF5 | MoF4 MoF5 MoF6 | TcF4 TcF 5 TcF6 | RuF3 RuF 4 RuF5 RuF6 | RhF3 RhF4 RhF5 RhF6 | PdF2 Pd[PdF6] PdF4 ?PdF6 | Ag2F AgF AgF2 AgF3 | CdF2 | InF InF3 | SnF2 SnF4 | SbF3 SbF5 | TeF4 ?Te2F10 TeF6 +TeO3 | IF IF3 IF5 IF7 +IO3 | XeF2 XeF4 XeF6 ?XeF8 | |
CsF | BaF2 | LuF3 | HfF4 | TaF5 | WF4 WF5 WF6 | ReF4 ReF5 ReF6 ReF7 | OsF4 OsF5 OsF6 ?OsF 7 ?OsF 8 | IrF2 IrF3 IrF4 IrF5 IrF6 | PtF2 Pt[PtF6] PtF4 PtF5 PtF6 | AuF AuF3 Au2F10 ?AuF6 AuF5•F2 | Hg2F2 HgF2 ?HgF4 | TlF TlF3 | PbF2 PbF4 | BiF3 BiF5 | ?PoF2 PoF4 PoF6 | AtF ?AtF3 ?AtF5 | RnF2 ?RnF 4 ?RnF 6 | |
FrF | RaF2 | LrF3 | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og | |
↓ | ||||||||||||||||||
LaF3 | CeF3 CeF4 | PrF3 PrF4 | NdF2 NdF3 NdF4 | PmF3 | SmF2 SmF3 | EuF2 EuF3 | GdF3 | TbF3 TbF4 | DyF2 DyF3 DyF4 | HoF3 | ErF3 | TmF2 TmF3 | YbF2 YbF3 | |||||
AcF3 | ThF3 ThF4 | PaF4 PaF5 | UF3 UF4 UF5 UF6 | NpF3 NpF4 NpF5 NpF6 | PuF3 PuF4 PuF5 PuF6 | AmF2 AmF3 AmF4 ?AmF6 | CmF3 CmF4 ?CmF6 | BkF3 BkF 4 | CfF3 CfF4 | EsF3 EsF4 ?EsF6 | Fm | Md | No |