Difluoromethane
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2008-07-03T08:11:56Z
VolkovBot
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robot Adding: [[de:Difluormethan]]
{{Chembox new
| ImageFileL1 = Difluoromethane-2D.svg
| ImageSizeL1 =
| ImageFileR1 = Difluoromethane-3D-vdW.png
| ImageSizeR1 =
| IUPACName = Difluoromethane
| OtherNames = Methylene fluoride, Methylene difluoride, Carbon fluoride hydride, HFC 32, R 32, FC 32, Freon 32, UN 3252
| Section1 = {{Chembox Identifiers
| CASNo = 75-10-5
| EINECS = 200-839-4
| PubChem = 6345
| SMILES = C(F)F
| InChI = 1/CH2F2/c2-1-3/h1H2
| RTECS = PA8537500
}}
| Section2 = {{Chembox Properties
| Formula = CH<sub>2</sub>F<sub>2</sub>
| MolarMass = 52.02 g/mol
| Appearance = Colorless gas
| Density = 2.72 kg/m<sup>3</sup> at 15 °C (59 °F)<br/>
2.163 kg/m<sup>3</sup> at 21.1 °C (70 °F)
| MeltingPt = −136 °C
| BoilingPt = −51.6 °C
| Solubility =
| VaporPressure = 1518.92 kPa at 21.1 °C (70 °F)
}}
| Section3 = {{Chembox Hazards
| EUClass = Extremely flammable ('''F+''')
| ExternalMSDS = [http://ptcl.chem.ox.ac.uk/MSDS/DI/difluoromethane.html MSDS at Oxford University]
| MainHazards =
| FlashPt =
| Autoignition = 648 °C
| RPhrases = {{R12}}
| SPhrases = {{S9}}, {{S16}}, {{S23}}
| NFPA-H = 1
| NFPA-F = 4
| NFPA-R = 1
| NFPA-O =
}}
}}
'''Difluoromethane''', also called '''HFC-32''' or '''R-32''', is an [[organic compound]] of the [[Haloalkane|dihalogenoalkane]] variety. It is based on [[methane]], except that two of the four [[hydrogen]] atoms have been replaced by [[fluorine]] atoms. Hence the formula is CH<sub>2</sub>F<sub>2</sub> instead of CH<sub>4</sub> for normal methane.
== Physical properties ==
{| class="wikitable"
! Property
! Value
|-
| [[Critical pressure]] (p<sub>c</sub>)
| 5.83 MPa
|-
| [[Critical temperature]] (T<sub>c</sub>)
| 78.45 °C (351 K)
|-
| [[Compressibility factor]] (Z)
| 0.9863
|-
| [[Specific heat capacity|Heat capacity]] at constant pressure (C<sub>p</sub>) at 21 °C (70 °F)
| 0.043 kJ·mol<sup>−1</sup>·K<sup>−1</sup>
|-
| [[Specific heat capacity|Heat capacity]] at constant volume (C<sub>V</sub>) at 21 °C (70 °F)
| 0.034 kJ·mol<sup>−1</sup>·K<sup>−1</sup>
|-
| [[Heat capacity ratio]] (κ)
| 1.253
|-
|}
== Uses ==
Difluoromethane is a [[refrigerant]] that has zero [[ozone depletion potential]]. Difluoromethane in an [[azeotrope|azeotropic]] mixture with [[pentafluoroethane]] is known as [[R-410A]], a common replacement for various [[chlorofluorocarbons]] (aka ''[[Freon]]'') in new [[refrigerant]] systems. Although it has zero ozone depletion potential, it has high [[global warming potential]], 550 times that of carbon dioxide, based on a 100-year time frame [http://www.maine.gov/dep/air/emissions/ghg-equiv.htm].
== See also ==
* [[Haloalkane]]
* [[Halomethane]]
* [[Dichloromethane]]
* [[Dibromomethane]]
* [[Diiodomethane]]
* [[Fluoromethane]]
* [[Fluoroform]] (Trifluoromethane)
* [[Tetrafluoromethane]]
== External links ==
* [http://www.fire.nist.gov/bfrlpubs/fire99/art047.html Flammability Measurements of Difluoromethane in Air at 100° C]
* [http://encyclopedia.airliquide.com/encyclopedia.asp?GasID=108 Difluoromethane at Gas Encyclopaedia]
* [http://www.nist.gov/kinetics/spectra/ir_spectra/CH2F2%20(HFC-32).pdf IR absorption spectra]
[[Category:Organofluorides]]
[[Category:Halomethanes]]
[[Category:Refrigerants]]
[[de:Difluormethan]]
[[ja:ジフルオロメタン]]
[[zh:二氟甲烷]]