ثانى أكسيد الكبريت

ثانى أكسيد الكبريت
Skeletal formula sulfur dioxide with assorted dimensions
Spacefill model of sulfur dioxide
The Lewis structure of sulfur dioxide (SO2), showing unshared electron pairs.
الأسماء
اسم أيوپاك
Sulfur dioxide
أسماء أخرى
Sulfurous anhydride
Sulfur(IV) oxide
المُعرِّفات
رقم CAS
3D model (JSmol)
مرجع بايلستاين 3535237
ChEBI
ChEMBL
ChemSpider
رقم EC
  • 231-195-2
مرجع Gmelin 1443
KEGG
عناوين مواضيع طبية MeSH {{{value}}}
رقم RTECS
  • WS4550000
UNII
UN number 1079, 2037
الخصائص
الصيغة الجزيئية SO 2
كتلة مولية 64.066 g mol−1
المظهر Colorless gas
الرائحة Pungent; similar to a just-struck match[1]
الكثافة 2.6288 kg m−3
نقطة الانصهار
نقطة الغليان
قابلية الذوبان في الماء 94 g/L[2]
forms sulfurous acid
ضغط البخار 237.2 kPa
الحموضة (pKa) 1.81
القاعدية (pKb) 12.19
القابلية المغناطيسية −18.2·10−6 cm3/mol
اللزوجة 0.403 cP (at 0 °C)
البنية
هندسة
إحداثية 		Digonal
الشكل الجزيئي Dihedral
Dipole moment 1.62 D
الكيمياء الحرارية
الإنتالپية المعيارية
للتشكل ΔfHo298 		−296.81 kJ mol−1
Standard molar
entropy So298 		248.223 J K−1 mol−1
المخاطر
سام T
توصيف المخاطر R23, R34, R50
تحذيرات وقائية (S1/2), S9, S26, S36/37/39, S45
NFPA 704 (معيـَّن النار)
Flammability code 0: لن يشتعل. مثل الماءHealth code 3: التعرض لفترة قصيرة قد يتسبب في جروح خطيرة مؤقتة أو باقية. مثل غاز الكلورReactivity code 0: مستقر في العادة، حتى تحت ظروف التعرض للنار، ولا يتفاعل مع الماء. مثل النيتروجين السائلSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
3
0
الجرعة أو التركيز القاتل (LD, LC):
3000 ppm (mouse, 30 min)
2520 ppm (rat, 1 hr)[4]
993 ppm (rat, 20 min)
611 ppm (rat, 5 hr)
764 ppm (mouse, 20 min)
1000 ppm (human, 10 min)
3000 ppm (human, 5 min)[4]
حدود التعرض الصحية بالولايات المتحدة (NIOSH):
PEL (المسموح)
 TWA 5 ppm (13 mg/m3)[3]
REL (الموصى به)
 TWA 2 ppm (5 mg/m3) ST 5 ppm (13 mg/m3)[3]
IDLH (خطر عاجل)
 100 ppm[3]
مركبات ذا علاقة
sulfur oxides ذات العلاقة
 Sulfur monoxide
Sulfur trioxide
مركـّبات ذات علاقة
 Ozone

Selenium dioxide
Sulfurous acid
Tellurium dioxide

ما لم يُذكر غير ذلك، البيانات المعطاة للمواد في حالاتهم العيارية (عند 25 °س [77 °ف]، 100 kPa).
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مراجع الجدول

ثاني أوكسيد الكبريت مركّب كيمياوي بالصيغة SO2. هذا الغاز المهم يعتبر الناتج الرئيسي من إحتراق الكبريت.
SO2 ينتج بواسطة البراكين وفي العمليات الصناعية المختلفة. ولأن الفحم و النفط يحتويان على كمّيات مختلفة من مركّبات الكبريت، فبالتالى يولّد إحتراقهم ثاني أوكسيد كبريت.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Structure and bonding

SO2 is a bent molecule with C2v symmetry point group. A valence bond theory approach considering just s and p orbitals would describe the bonding in terms of resonance between two resonance structures.

Two resonance structures of sulfur dioxide

The sulfur–oxygen bond has a bond order of 1.5. There is support for this simple approach that does not invoke d orbital participation.[5] In terms of electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1.


التواجد

The blue auroral glows of Io's upper atmosphere are caused by volcanic sulfur dioxide.

As an air pollutant

A sulfur dioxide plume from the Halemaʻumaʻu vent, glows at night

Sulfur dioxide is a noticeable component in the atmosphere, especially following volcanic eruptions.[6] According to the United States Environmental Protection Agency,[7] the amount of sulfur dioxide released in the U.S. per year was:

A collection of estimates of past and future anthropogenic global sulphur dioxide emissions. The Cofala et al. estimates are for sensitivity studies on SO2 emission policies, CLE: Current Legislation, MFR: Maximum Feasible Reductions. RCPs (Representative Concentration Pathways) are used in CMIP5 simulations for latest (2013–2014) IPCC 5th assessment report.
Year SO2
1970 31,161,000 short tons (28.3 Mt)
1980 25,905,000 short tons (23.5 Mt)
1990 23,678,000 short tons (21.5 Mt)
1996 18,859,000 short tons (17.1 Mt)
1997 19,363,000 short tons (17.6 Mt)
1998 19,491,000 short tons (17.7 Mt)
1999 18,867,000 short tons (17.1 Mt)

Sulfur dioxide is a major air pollutant and has significant impacts upon human health.[8] In addition, the concentration of sulfur dioxide in the atmosphere can influence the habitat suitability for plant communities, as well as animal life.[9] Sulfur dioxide emissions are a precursor to acid rain and atmospheric particulates. Due largely to the US EPA’s Acid Rain Program, the U.S. has had a 33% decrease in emissions between 1983 and 2002. This improvement resulted in part from flue-gas desulfurization, a technology that enables SO2 to be chemically bound in power plants burning sulfur-containing coal or oil. In particular, calcium oxide (lime) reacts with sulfur dioxide to form calcium sulfite:

CaO + SO2 → CaSO3

Aerobic oxidation of the CaSO3 gives CaSO4, anhydrite. Most gypsum sold in Europe comes from flue-gas desulfurization.

Sulfur can be removed from coal during burning by using limestone as a bed material in fluidized bed combustion.[10]

Sulfur can also be removed from fuels before burning, preventing formation of SO2 when the fuel is burnt. The Claus process is used in refineries to produce sulfur as a byproduct. The Stretford process has also been used to remove sulfur from fuel. Redox processes using iron oxides can also be used, for example, Lo-Cat[11] or Sulferox.[12]

Sulfur dioxide in the world on April 15th, 2017. Note that sulfur dioxide moves through the atmosphere with prevailing winds and thus local sulfur dioxide distributions vary day to day with weather patterns and seasonality.

Fuel additives such as calcium additives and magnesium carboxylate may be used in marine engines to lower the emission of sulfur dioxide gases into the atmosphere.[13]

As of 2006, China was the world's largest sulfur dioxide polluter, with 2005 emissions estimated to be 25,490,000 short tons (23.1 Mt). This amount represents a 27% increase since 2000, and is roughly comparable with U.S. emissions in 1980.[14]

Ingestion

In the United States, the Center for Science in the Public Interest lists the two food preservatives, sulfur dioxide and sodium bisulfite, as being safe for human consumption except for certain asthmatic individuals who may be sensitive to them, especially in large amounts.[15] Symptoms of sensitivity to sulfiting agents, including sulfur dioxide, manifest as potentially life-threatening trouble breathing within minutes of ingestion.[16]

انظر أيضاً

المراجع

  1. ^ Sulfur dioxide, U.S. National Library of Medicine
  2. ^ قالب:RubberBible87th
  3. ^ أ ب ت NIOSH Pocket Guide to Chemical Hazards 0575
  4. ^ أ ب "Sulfur dioxide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ^ Cunningham, Terence P.; Cooper, David L.; Gerratt, Joseph; Karadakov, Peter B.; Raimondi, Mario (1997). "Chemical bonding in oxofluorides of hypercoordinatesulfur". Journal of the Chemical Society, Faraday Transactions. 93 (13): 2247–2254. doi:10.1039/A700708F. {{cite journal}}: Unknown parameter |lastauthoramp= ignored (|name-list-style= suggested) (help)
  6. ^ Volcanic Gases and Their Effects. Volcanoes.usgs.gov. Retrieved on 2011-10-31.
  7. ^ National Trends in Sulfur Dioxide Levels, United States Environmental Protection Agency.
  8. ^ Sulfur Dioxide. United States Environmental Protection Agency
  9. ^ Hogan, C. Michael (2010). "Abiotic factor" in Encyclopedia of Earth. Emily Monosson and C. Cleveland (eds.). National Council for Science and the Environment. Washington DC
  10. ^ Lindeburg, Michael R. (2006). Mechanical Engineering Reference Manual for the PE Exam. Belmont, C.A.: Professional Publications, Inc. pp. 27–3. ISBN 978-1-59126-049-3.
  11. ^ FAQ’s About Sulfur Removal and Recovery using the LO-CAT® Hydrogen Sulfide Removal System. gtp-merichem.com
  12. ^ Process screening analysis of alternative gas treating and sulfur removal for gasification. (December 2002) Report by SFA Pacific, Inc. prepared for U.S. Department of Energy (PDF) . Retrieved on 2011-10-31.
  13. ^ May, Walter R. Marine Emissions Abatement. SFA International, Inc., p. 6.
  14. ^ China has its worst spell of acid rain, United Press International (2006-09-22).
  15. ^ "Center for Science in the Public Interest – Chemical Cuisine". Retrieved March 17, 2010.
  16. ^ "California Department of Public Health: Food and Drug Branch: Sulfites" (PDF). Archived from the original (PDF) on July 23, 2012. Retrieved September 27, 2013. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

وصلات خارجية

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