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1,1,1,2-Tetrafluoroethane
From Wikipedia, the free encyclopedia
| 1,1,1,2-Tetrafluoroethane | |
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| IUPAC name | 1,1,1,2-tetrafluoroethane |
| Other names | Genetron 134a HFC-134a R-134a Freon 134a Norflurane |
| Identifiers | |
| CAS number | |
| RTECS number | KI8842500 |
| SMILES | FC(F)(F)C(F) |
| Properties | |
| Molecular formula | C2H2F4 |
| Molar mass | 102.03 g/mol |
| Appearance | Colorless gas. |
| Density | 0.00425 g/cm³, gas. |
| Melting point |
-103.3°C (169.85 K) |
| Boiling point |
-26.3°C (246.85 K) |
| Solubility in water | Insoluble. |
| Structure | |
| Molecular shape | Planar. |
| Hazards | |
| Main hazards | Asphyxiant. |
| NFPA 704 |
 1
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1
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| S-phrases | (S2), S23, S24/25, S51. |
| Flash point | Non-flammable. |
| Related Compounds | |
| Related refrigerants | Difluoromethane Pentafluoroethane |
| Related compounds | 1,1,2,2,2-pentafluoroethane 2-Chloro- 1,1,1,2-tetrafluoroethane 1,1,1-Trichloroethane |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane, R-134a, Genetron 134a, Freon 134a or HFC-134a, is a haloalkane refrigerant without an ozone depletion potential and thermodynamic properties similar to R-12 (dichlorodifluoromethane). It has the formula CH2FCF3, and a boiling point of −26.3 °C (−15.34 °F).
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1,1,1,2-Tetrafluoroethane is an inert gas used primarily as a "high-temperature" refrigerant for domestic refrigeration and automobile air conditioners. Other uses include plastic foam blowing, as a cleaning solvent and as a propellant for the delivery of pharmaceuticals (e.g. bronchodilators), gas dusters, and in air driers, that is, for removing the moisture from compressed air. Moisture present in compressed air has a harmful effect on pneumatic systems. Tetrafluoroethane has also been used to cool computers in some overclocking attempts. It is also commonly used as a power source for airsoft airguns.
Recently, R-134a has been subject to use restrictions due to its theorized contribution to climate change. In the EU, it will be banned as from 2011 in all new cars[1], and California may prohibit the sale of canned HFC-134a to individuals to avoid non-professional recharge of the air conditioner.[2]
R-134a first appeared in the early 1990s as a replacement for Dichlorodifluoromethane (R-12), which has significant ozone depleting properties.[3] R-134a has been atmospherically modeled for its impact on depleting ozone and as a contributor to global warming. Research suggests that over the past 10 years the concentration of 1,1,1,2-tetrafluoroethane has increased significantly in the Earth atmosphere, with a recent study revealing a doubling in atmospheric concentration between 2001-2004.[4] It has insignificant ozone depletion potential (ozone layer), significant global warming potential (GWP100 = 1300) and negligible acidification potential (acid rain). 1,1,1,2-Tetrafluoroethane is slowly converted to trifluoroacetic acid through a radical reaction in the upper atmosphere and leads to a detectable amount of several ng/L in acid rain.[5]
Contact of tetrafluoroethane with flames or hot surfaces in excess of 250°C (482°F) may cause vapor decomposition and the emission of toxic gases including hydrogen fluoride and carbonyl halides.[6] Tetrafluoroethane itself has an LC50 (lethal concentration for 50% of subjects) in rats of 1,500 g/m³, making it relatively non-toxic. However, its gaseous form is denser than air, and will displace air in the lungs. This can result in asphyxiation if excessively inhaled.[7][8]
Aerosol cans containing tetrafluoroethane, when inverted, become effective freeze sprays. Under pressure, tetrafluoroethane is compressed into a liquid, which upon vaporization absorbs a significant amount of thermal energy. As a result, it will greatly lower the temperature of any object it contacts as it evaporates. This can result in frostbite when it contacts skin.
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This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (November 2007) |
| Physical Properties | HCF-134a |
|---|---|
| Boiling Point at 1 atm (101.3 kPa or 1.013 bar) | –15.34 °F (–26.3 °C) |
| Freezing Point | –153.9 °F (–103.3 °C) |
| Critical Temperature | 213.9 °F (101.1 °C) |
| Critical Pressure | 4060 kPa (588.9 lb/in² abs) |
| Critical Volume | 1.94 × 10-3 m³/kg (0.031 ft³/lb) |
| Critical Density | 515.3 kg/m³ (32.17 lb/ft³) |
| Density (Liquid) at 25 °C (77 °F) | 1206 kg/m³ (75.28lb/ft³) |
| Density (Saturated Vapor) at boiling point | 5.25 kg/m³ (0.328 lb/ft³) |
| Heat Capacity (Liquid) at 25 °C (77 °F) | 0.339 kJ/kg·K or Btu/(lb) (°F) |
| Heat Capacity (Vapor at Constant Pressure) at 25 °C (77 °F) and 1 atm (101.3 kPa or 1.013 bar) | 0.204 kJ/kg·K or Btu/(lb) (°F) |
Vapor Pressure at 25 °C (77 °F) kPa 666.1 bar 6.661
psia 96.61
Heat of Vaporization at Boiling Point kJ/kg 217.2 Btu/lb 93.4
Thermal Conductivity at 25 °C (77 °F)
Liquid W/m·K 0.0824
Btu/hr·ft°F 0.0478
Vapor at 1 atm (101.3 kPa or 1.013 bar) W/m·K 0.0145 Btu/hr·ft°F 0.00836
Viscosity at 25 °C (77 °F) Liquid mPa·S (cP) 0.202 Vapor at 1 atm (101.3 kPa or 1.013 bar) mPa·S (cP) 0.012
Solubility of HFC-134a wt% 0.15 in Water at 25 °C (77 °F) and 1 atm (101.3 kPa or 1.013 bar)
Solubility of Water in HFC-134a wt% 0.11 at 25 °C (77 °F)
Flammability Limits in Air at 1 atm (101.3 kPa or 1.013 bar) vol % None
Autoignition Temperature °C 770 °F 1,418
Ozone Depletion Potential — 0
Halocarbon Global Warming Potential (HGWP) — 0.28 (For CFC-11, HGWP = 1)
Global Warming Potential (GWP) — 1,200 (100 yr ITH. For CO2, GWP = 1)
TSCA Inventory Status — Reported/Included
Toxicity AEL* (8- and 12-hr TWA) ppm (v/v) 1,000
- AEL (Acceptable Exposure Limit) is an airborne inhalation exposure limit established by DuPont that specifies time-weighted
average concentrations to which nearly all workers may be repeatedly exposed without adverse effects. Note: kPa is absolute pressure.
- ^ European Directive 2006/40/EC relating to emissions from air-conditioning systems in motor vehicles
- ^ Early Action Measure California: Use ban of canned HFC-134a
- ^ Franklin J (1993). "The Atmospheric Degradation and Impact of 1,1,1,2-Tetrafluorethane (Hydrofluorocarbon 134a)". Chemosphere 27: 1565-1601. doi:10.1016/0045-6535(93)90251-Y.
- ^ Greenhouse gas monitoring at the Zeppelin station - Annual report 2004 (TA-2110/2005). Norwegian Institute for Air Research. Retrieved on 2006-01019.
- ^ von Sydow L, Grimvall AB, Borén HB, Laniewski K, Nielsen AT (2000). "Natural Background Levels of Trifluoroacetate in Rain and Snow". Enviro Sci Technol 34: 3115-3118. doi:10.1021/es9913683.
- ^ Honeywell International (December 2005). "MSDS # GTRN-0047 For Genetron® 134aUV".
- ^ Alexander D. J, Libretto S. E. (1995). "An overview of the toxicology of HFA-134a (1,1,1,2-tetrafluoroethane)". Hum. Exp. Toxicol. 14: 715-20.
- ^ G. E. Millward, E. Tschuikow-Roux (1972). "Kinetic analysis of the shock wave decomposition of 1,1,1,2-tetrafluoroethane" 76 (3): 292 - 298. doi:10.1021/j100647a002.
