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Sulfur dioxide
Other names sulfur(IV) oxide; sulfurous anhydride
Identifiers
CAS number [7446-09-5]
RTECS number WS4550000
Properties
Molecular formula SO2
Molar mass 64. CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to Registry of Toxic Effects of Chemical Substances ( RTECS) is a Database of Toxicity information compiled from the open scientific literature without reference A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) 054 g mol−1
Appearance colourless gas
Density 2. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 551 g/L, gas
Melting point

−72. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. 4 °C (200. 75 K)
Boiling point

−10 °C (263 K)
Solubility in water 9. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Water is a common Chemical substance that is essential for the survival of all known forms of Life. 4 g/100 mL (25 °C)
Acidity (pKa) 1. 81
Structure
Molecular shape Bent 120°[1]
Dipole moment 1. Molecular geometry or molecular structure is the three- Dimensional arrangement of the Atoms that constitute a Molecule. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a 63 D
Hazards
EU classification Toxic
NFPA 704
 
3
 
 
R-phrases R23 R34
S-phrases (S1/2) S9 S26 S36/37/39 S45
Flash point non-flammable
Related compounds
Related compounds Sulfur trioxide; sulfuric acid
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Sulfur dioxide (also sulphur dioxide) is the chemical compound with the formula SO2. The debye (symbol D) is a non- SI, CGS unit of electrical dipole moment. Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws regulations and administrative provisions relating to the classification packaging and labelling Symbolism The four divisions are typically color-coded with blue indicating level of Health Hazard, red indicating R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. The flash point of a flammable liquid is the lowest Temperature at which it can form an ignitable mixture in air Sulfur trioxide (also spelled sulphur trioxide) is the chemical compound with the formula SO3 Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. In Chemistry, the standard state of a material is its state at 1 bar (100 Kilopascals exactly A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. SO2 is produced by volcanoes and in various industrial processes. Plate tectonics and hotspots Divergent plate boundaries At the Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide. Petroleum ( L petroleum, from Greek πετρέλαιον, lit Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. Nitrogen dioxide is the Chemical compound with the formula N[[Oxygen O]]2 Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Acid rain is Rain or any other form of precipitation that is unusually Acidic It has harmful effects on plants aquatic animals and infastructure [2] This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.

Contents

Preparation

Sulfur dioxide can be prepared by burning sulfur:

S8 + 8 O2 → 8 SO2

The combustion of hydrogen sulfide and organosulfur compounds proceeds similarly. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S.

2 H2S(g) + 3 O2(g) → 2 H2O(g) + 2 SO2(g)

The roasting of sulfide ores such as iron pyrites, sphalerite (zinc blende) and cinnabar (mercury sulfide) also releases SO2:

4 FeS2(s) + 11 O2(g) → 2 Fe2O3(s) + 8 SO2(g)
2 ZnS(s) + 3 O2(g) → 2 ZnO(s) + 2 SO2(g)
HgS(s) + O2(g) → Hg(g) + SO2(g)

Sulfur dioxide is a by-product in the manufacture of cement: CaSiO3 and CaSO4 is heated with coke and sand in this process:

2 CaSO4(s) + 2SiO2(s) + C(s) → 2 CaSiO3(s) + 2 SO2(g) + CO2(g)

Action of hot sulfuric acid on copper turnings produces sulfur dioxide. Sphalerite (( Zn, Fe) S) is a Mineral that is the chief Ore of Zinc. Cinnabar, sometimes written cinnabarite, is a name applied to red Mercury(II sulfide ( Hg[[sulfide S]] or native Vermilion, the common Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 In the most general sense of the word a cement is a binder a substance which sets and hardens independently and can bind other materials together Calcium silicates are a set of four compounds obtained by reacting Calcium oxide and silica in various ratios Calcium sulfate is a common laboratory and industrial chemical Coke is a solid Carbonaceous material derived from Destructive distillation of low-ash low-sulfur Bituminous coal. Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Swarf (or turnings or chips are shavings and chippings of metal—the debris or waste resulting from Metalworking operations

Cu(s) + 2H2SO4(aq) → CuSO4(aq) + SO2(g) + 2H2O(l)

Structure and bonding

SO2 is a bent molecule with C2v symmetry point group. Group theory is a mathematical discipline the part of Abstract algebra that studies the Algebraic structures known as groups. In terms of electron-counting formalisms, the sulfur atom has an oxidation state of +4, a formal charge of 0, and is surrounded by 5 electron pairs and can be described as a hypervalent molecule. Electron counting is a formalism used for classifying compounds and for explaining or predicting electronic structure and bonding. In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. Chemistry, a formal charge (FC is a Partial charge on an Atom in a Molecule assigned by assuming that Electrons in a Chemical lone pair is a (valence electron pair without bonding or sharing with other Atoms They are found in the outermost Electron shell of an atom so lone pairs A hypervalent molecule is a Molecule that contains one or more typical elements ( group 1 2 13-18 formally bearing more than eight Electrons in their From the perspective of molecular orbital theory, most of these valence electrons are engaged in S-O bonding. In Chemistry, molecular orbital theory ( MO theory) is a method for determining molecular structure in which Electrons are not assigned to individual

three resonance structures of sulfur dioxide

The S-O bonds are shorter in SO2 (143. Resonance in Chemistry is a theory used to represent and model certain types of non-classical Molecular structures Resonance is a key component 1 pm) than in sulfur monoxide, SO (148. Sulfur monoxide is a Chemical compound with formula and CAS number 13827-32-2 1 pm), whereas the O-O bonds are longer in O3 (127. 8 pm) than in dioxygen, O2 (120. 7 pm). The mean bond energy is greater in SO2 (548 kJ mol−1) than in SO (524 kJ mol−1), whereas its is less in O3 (297 kJ mol−1) than in O2 (490 kJ mol−1). These pieces of evidence lead chemists to conclude that the S-O bonds in sulfur dioxide have a bond order of at least 2, unlike the O-O bonds in ozone, which have a bond order of 1. Bond order is the number of bonds between a pair of atoms For example in Nitrogen N≡N the bond order is 3 in Acetylene H−C≡C−H the bond order between the OZONE is an object oriented Operating system written in the C programming language. 5[3]

Reactions

Treatment of basic solutions with sulfur dioxide affords sulfite salts:

SO2 + 2 NaOH → Na2SO3 + H2O

Featuring sulfur in the +4 oxidation state, sulfur dioxide is a reducing agent. Sulfites (also sulphites) are compounds that contain the sulfite Ion S[[oxygen O]]32− A reducing agent (also called a reductant or reducer) is the element or a compound in a Redox (reduction-oxidation reaction (see Electrochemistry It is oxidized by halogens such as chlorine to give the sulfuryl halides:

SO2 + Cl2 → SO2Cl2

However, on rare occasions, it can also act as an oxidising agent: in the Claus process, sulfur dioxide is reduced by hydrogen sulfide to give elemental sulfur:

SO2 + 2 H2S → 3 S + 2 H2O

Sulfur dioxide can act as a metal binding ligand, typically where the transition metal is in oxidation state 0 or +1. Sulfuryl chloride is SO2Cl2 a compound composed of Sulfur, Oxygen, and Chlorine. An oxidizing agent or oxidising agent (also called an oxidant, oxidizer or oxidiser) can be defined as either a Chemical compound The Claus process is the most significant gas desulfurizing process recovering elemental Sulfur from gaseous Hydrogen sulfide. In Chemistry, a ligand is either an Atom, Ion, or Molecule (see also Functional group) that bonds to a central metal generally [4] Up to 9 different bonding modes have been determined which include[4]:

Uses

As a preservative

Sulfur dioxide is sometimes used as a preservative for dried apricots and other dried fruits due to its antimicrobial properties, it is sometimes called E220 when used in this way. The term hapticity is used to describe how a group of contiguous atoms of a ligand are coordinated to a central atom The term hapticity is used to describe how a group of contiguous atoms of a ligand are coordinated to a central atom The term hapticity is used to describe how a group of contiguous atoms of a ligand are coordinated to a central atom A preservative is a natural or synthetic chemical that is added to products such as foods pharmaceuticals paints biological samples wood etc The Apricot ( Prunus armeniaca, "Armenian plum" in Latin syn Dried fruit is fruit that has been dried, either naturally or through use of a machine such as a Food dehydrator. An antimicrobial is a substance that kills or inhibits the growth of Microbes such as Bacteria, Fungi, or Viruses. E numbers are number codes for Food additives and are usually found on Food labels throughout the European Union. The preservative is used to maintain the appearance of the fruit and prevent rotting. Decomposition (or spoilage) refers to the break down of tissue of a formerly living Organism into simpler forms of matter Its presence can give fruit a distinctive chemical taste. Taste (or more formally gustation) is a form of direct Chemoreception and is one of the traditional five Senses

In winemaking

Sulfur dioxide is a very important compound in winemaking, and is designated as parts per million in wine, E number: E220. E numbers are number codes for Food additives and are usually found on Food labels throughout the European Union. [5] It is present even in so-called unsulphurated wine at concentrations of up to 10 milligrams per litre. [6] It serves as an antibiotic and antioxidant, protecting wine from spoilage by bacteria and oxidation. It also helps to keep volatile acidity at desirable levels. Sulfur dioxide is responsible for the words "contains sulfites" found on wine labels. Wines with SO2 concentrations below 10ppm do not require "contains sulfites" on the label by US and EU laws. The upper limit of SO2 allowed in wine is 350ppm in US, in the EU is 160 ppm for red wines and 210 ppm for white and rosé wines. A rosé (From French rosé ‘pinkish’ Wine has some of the color typical of a red wine but only enough to turn it pink In low concentrations SO2 is mostly undetectable in wine, but at over 50ppm, SO2 becomes evident in the nose and taste of wine.

SO2 is also a very important element in winery sanitation. Wineries and equipment must be kept very clean, and because bleach cannot be used in a winery, a mixture of SO2, water, and citric acid is commonly used to clean hoses, tanks, and other equipment to keep it clean and free of bacteria.

As a reducing bleach

Sulfur dioxide is also a good reductant. A reducing agent (also called a reductant or reducer) is the element or a compound in a Redox (reduction-oxidation reaction (see Electrochemistry In the presence of water, sulfur dioxide is able to decolorize substances. Specifically it is a useful reducing bleach for papers and delicate materials such as clothes. A bleach is a Chemical that removes color or whitens often via Oxidation. Paper is thin material mainly used for writing upon printing upon or packaging This bleaching effect normally does not last very long. Oxygen in the atmosphere reoxidizes the reduced dyes, restoring the color. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the

Precursor to sulfuric acid

Sulfur dioxide is also used to make sulfuric acid, being converted to sulfur trioxide, and then to oleum, which is made into sulfuric acid. Sulfur trioxide (also spelled sulphur trioxide) is the chemical compound with the formula SO3 Oleum ( Latin oleum = "oil" or fuming sulfuric acid refers to a solution various compositions of Sulfur trioxide in Sulfuric Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Sulfur dioxide for this purpose is made when sulfur combines with oxygen. The method of converting sulfur dioxide to sulfuric acid is called the contact process. The contact process is the current method of producing Sulfuric acid in the high concentrations needed for industrial processes

Biochemical and biomedical roles

Sulfur dioxide is toxic in large amounts. It or its conjugate base bisulfite is produced biologically as an intermediate in both sulfate-reducing organisms and in sulfur oxidizing bacteria as well. Sulfur dioxide has no role in mammalian biology. Sulfur dioxide blocks nerve signals from the pulmonary stretch receptors (PSR's) and abolishes the Hering-Breuer inflation reflex. Pulmonary stretch receptors are Mechanoreceptors found in the lungs.

As a refrigerant

Being easily condensed and with a high heat of evaporation, sulfur dioxide is a candidate material for refrigerants. Prior to the development of freons, sulfur dioxide was used as a refrigerant in home refrigerators. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back

As a reagent and solvent

Sulfur dioxide is a versatile inert solvent that has been widely used for dissolving highly oxidizing salts. It is also used occasionally as a source of the sulfonyl group in organic synthesis. Organic synthesis is a special branch of Chemical synthesis and is concerned with the construction of Organic compounds via Organic reactions Organic Treatment of aryldiazonium salts with sulfur dioxide affords the corresponding aryl sulfonyl chloride. Diazonium compounds or diazonium salts are a group of Organic compounds sharing a common Functional group with the characteristic structure of R-N2+ [7]

Dechlorination

In municipal wastewater treatment sulfur dioxide is used to treat chlorinated wastewater prior to release. Sulfur dioxide reacts with free and combined chlorine to form negatively charged chloride ions. [8]

Emissions

Sulfur dioxide emissions from the Halema`uma`u vent, glows at night
Sulfur dioxide emissions from the Halema`uma`u vent, glows at night

According to the U.S. EPA (as presented by the 2002 World Almanac or in chart form[9]), the following amount of sulfur dioxide was released in the U.S. per year, measured in thousands of short tons:

*1999 18,867
*1998 19,491
*1997 19,363
*1996 18,859
*1990 23,678
*1980 25,905
*1970 31,161

Due largely to the US EPA’s Acid Rain Program, the U. The United States of America —commonly referred to as the The short ton ( S/T) is a unit of mass equal to 2000 lb (around 907 The United States of America —commonly referred to as the The Acid Rain Program is a market-based initiative taken by the United States Environmental Protection Agency in an effort to reduce overall atmospheric levels of Sulfur S. has witnessed a 33 percent decrease in emissions between 1983 and 2002. This improvement resulted from flue gas desulfurization, a technology that enables SO2 to be chemically bound in power plants burning sulfur-containing coal or oil. Flue gas desulfurization (FGD is the technology used for removing Sulfur dioxide (SO2 from the exhaust flue gases in power plants that A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of Petroleum ( L petroleum, from Greek πετρέλαιον, lit In particular, calcium oxide (lime) reacts with sulfur dioxide to form calcium sulfite:

CaO + SO2 → CaSO3

Aerobic oxidation converts this CaSO3 into CaSO4, gypsum. Calcium oxide ( CaO) commonly known as burnt lime, lime or quicklime, is a widely used Chemical compound. Calcium sulfite, or calcium sulphite, is a chemical compound which is the salt of Calcium cation and Sulfite anion with the molecular formula Gypsum is a very soft Mineral composed of Calcium sulfate dihydrate with the Chemical formula Ca[[sulfur S]] O 4·2 Most gypsum sold in Europe comes from flue gas desulfurization.

New fuel additive catalysts, such as ferox, are being used in gasoline and diesel engines in order to lower the emission of sulfur oxide gases into the atmosphere. Ferox is a fuel additive It was developed by Wesley Parish in 1985 from work done on experimental burn rate modifiers for solid rocket propellant systems used in the Aerospace This is also done by forcing the sulfur into stable mineral salts and mixed mineral sulfates as opposed to sulfuric acid and sulfur oxides.

As of 2006, China is the world's largest sulfur dioxide polluter, with 2005 emissions estimated to be 25. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National 49 million tons. This amount represents a 27% increase since 2000, and is roughly comparable with U. S. emissions in 1980[10].

Al-Mishraq, an Iraqi sulfur plant, was the site of a 2003 disaster resulting in the release of massive amounts of sulfur dioxide into the atmosphere. Al-Mishraq is a state run sulfur plant near Mosul, Iraq. In June 2003 it was the site of the largest man-made release of Sulfur dioxide ever recorded when

Temperature dependence of aqueous solubility

22 g/100ml (0 °C) 15 g/100ml (10 °C)
11 g/100ml (20 °C) 9. 4 g/100 ml (25 °C)
8 g/100ml (30 °C) 6. 5 g/100ml (40 °C)
5 g/100ml (50 °C) 4 g/100ml (60 °C)
3. 5 g/100ml (70 °C) 3. 4 g/100ml (80 °C)
3. 5 g/100ml (90 °C) 3. 7 g/100ml (100 °C)


Threats to Health

Sulfur dioxide acts as an acid. Inhalation results in labored breathing, coughing, and/or a sore throat and may cause permanent pulmonary damage. When mixed with water and contacted by skin, frostbite may occur. When it makes contact with eyes, redness and pain will occur. [11]

References

  1. ^ Table of Geometries based on VSEPR
  2. ^ Holleman, A. F. ; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  3. ^ Greenwood, N. N. ; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.   p. 700
  4. ^ a b Greenwood, N. N. ; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.  
  5. ^ Current EU approved additives and their E Numbers, The Food Standards Agency website.
  6. ^ Sulphites in wine, MoreThanOrganic. com.
  7. ^ R. V. Hoffman “m-Trifluoromethylbenzenesulfonyl chloride” Organic Syntheses, Collected Volume 7, p. 508 (1990). http://www.orgsyn.org/orgsyn/pdfs/CV7P0508.pdf.
  8. ^ Tchobanoglous, George. Wastewater Engineering. 3rd ed. New York: Mc Graw Hill, 1979.
  9. ^ National Trends in Sulfur Dioxide Levels, United States Environmental Protection Agency.
  10. ^ China has its worst spell of acid rain, United Press International.
  11. ^ SULPHUR DIOXIDE, International Labour Organization. The International Labour Organization

See also

External links

Sulfur trioxide (also spelled sulphur trioxide) is the chemical compound with the formula SO3 The sulfur-iodine cycle (S-I cycle is a series of thermochemical processes used to produce hydrogen. The National Ambient Air Quality Standards (NAAQS are standards established by the United States Environmental Protection Agency that apply for outdoor Air Homer City Generating Station is a 2- GW coal-burning power station near Homer City, in Indiana County, Pennsylvania, USA

Dictionary

sulfur dioxide

-noun

  1. (inorganic chemistry) A toxic gas, of molecular formula SO2 that is found in the emissions of volcanos and those of burning coal or petroleum; dissolves in water to form sulfurous acid and, in the presence of oxygen, sulfuric acid, and is thus responsible for acid rain.
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