Oxygen difluoride

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Oxygen difluoride
Structure and dimensions of the oxygen difluoride molecule
Space-filling model of the oxygen difluoride molecule
Identifiers
CAS number 7783-41-7 YesY
PubChem 24547
ChemSpider 22953 YesY
EC number 231-996-7
ChEBI CHEBI:30494 YesY
RTECS number RS2100000
Jmol-3D images Image 1
Properties
Molecular formula OF2
Molar mass 53.9962 g/mol
Appearance colorless gas, pale yellow liquid when condensed
Odor peculiar, foul odor
Density 1.90 g/cm3 (-224° C, liquid),
1.719 g/cm3 (-183° C, liquid), 1.521 g/cm3 (liquid at −145 °C), 1.88 g/l (gas at room temperature)
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]
Thermochemistry
Specific
heat capacity
C
43.3 J/mol K
Std molar
entropy
So298
246.98 J/mol K
Std enthalpy of
formation
ΔfHo298
24.5 kJ mol−1
Gibbs free energy ΔG 42.5 kJ/mol
Related compounds
Related compounds HFO
O2F2
NHF2
NF3
SCl2
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Oxygen difluoride is the chemical compound with the formula OF2. As predicted by VSEPR theory, the molecule adopts a "bent" molecular geometry similar to that of water, but it has very different properties, being a strong oxidizer.

Preparation[edit]

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.[2][3] 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

Reactions[edit]

Its powerful oxidizing properties are suggested by the oxidation number of +2 for the oxygen atom, which is unusual. Above 200 °C, OF2 decomposes to oxygen and fluorine via a radical mechanism.

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 (aq) + H2O (l) → 2 HF (aq) + O2 (g)

Oxygen difluoride oxidizes sulfur dioxide to sulfur trioxide[citation needed]:

OF2 + SO2 → SO3 + F2

However, in the presence of UV radiation the products are sulfuryl fluoride, SO
2
F
2
, and pyrosulfuryl fluoride, S
2
O
5
F
2
:

OF2 + 2 SO2S
2
O
5
F
2

Popular culture[edit]

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.

Safety[edit]

OF2 is a dangerous chemical, as is the case for any strongly oxidizing gas.

References[edit]

External links[edit]