Sulfur dioxide molar mass

Sulfur dioxide molar massis 64.0638 g/mol. The chemical substance with the formula SO2 is sulphur dioxide (IUPAC approved spelling) or sulphur dioxide (traditional Commonwealth English). The stench of burning matches is caused by this poisonous gas. . It is created as a by-product of copper mining and the combustion of sulfur-bearing fossil fuels, and it is released naturally by volcanic activity. The odor of sulfur dioxide is nitric acid-like.

Molar mass of Sulfur Dioxide

Structure and Bonding of Sulfur Dioxide (SO2)

SO2 is a C2v symmetry point group bent molecule. The bonding would be described in terms of resonance between two resonance structures using a valence bond theory method using just s and p orbitals.

Sulfur dioxide has two resonance configurations.

The bond order of the sulfur–oxygen bond is 1.5. This basic technique, which does not require orbital involvement, has some support. According to electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1.

Occurrence of Sulfur Dioxide (SO2)

Sulfur dioxide is present on Earth in extremely modest proportions and at around 1 ppm in the atmosphere.

Sulfur dioxide may be found in varying proportions on other planets, the most notable of which being the atmosphere of Venus, where it is the third-most prevalent atmospheric gas at 150 parts per million.

It combines with water to generate sulfuric acid clouds, which are an important part of the planet’s global sulfur cycle and contribute to global warming. Though it only exists in small proportions, it has been identified as a crucial component in the warming of early Mars, with estimations of concentrations in the lower atmosphere as high as 100 ppm.

Its major source is assumed to be volcanic on both Venus and Mars, as it is on Earth. The atmosphere of Io, Jupiter’s natural satellite, contains 90% sulfur dioxide, and tiny quantities are assumed to exist in Jupiter’s atmosphere.

It’s predicted to be abundant as ice on the Galilean moons—as subliming ice or frost on Io’s trailing hemisphere, and in the crust and mantle of Europa, Ganymede, and Callisto, potentially even in liquid form and easily reacting with water.

Production of Sulfur Dioxide (SO2)

Sulfur dioxide is primarily used in the production of sulfuric acid (see contact process). In 1979, 23.6 million metric tons (26,014,547 US short tons) of sulfur dioxide were utilized for this purpose in the United States, compared to 150 thousand metric tons (165,347 US short tons) for other reasons.

The burning of elemental sulfur produces the majority of sulfur dioxide. Sulfur dioxide is also created when pyrite and other supplied ores are roasted in the air.

Routes of Combustion

Sulfur dioxide is produced by the combustion of sulfur or sulfur-containing materials:

S + O2 → SO2, ΔH = −297 kJ/mol

Liquefied sulfur (140–150 °C, 284–302 °F) is sprayed via an atomizing nozzle to produce fine sulfur droplets with a wide surface area during combustion. The process is exothermic, resulting in temperatures of 1000–1600 °C (1832–2912 °F) during combustion. Steam generating recovers a large portion of the heat produced, which may then be turned to electricity.

Hydrogen supplied sulfur compounds both burn in the same way. Consider the following scenario:

2 H2S + 3 O2 → 2 H2O + 2 SO2

Sulfide ores such as pyrite, sphalerite, and cinnabar are also roasted, releasing SO2.

  • 4 FeS2 + 11 O2 → 2 Fe2O3 + 8 SO2
  • 2 ZnS + 3 O2 → 2 ZnO + 2 SO2
  • HgS + O2 → Hg + SO2
  • 4 FeS + 7O2 → 2 Fe2O3 + 4 SO2

Volcanic eruptions, the biggest producer of sulfur dioxide, are caused by a mixture of these processes. Thousands of tons of SO2 can be released during these incidents.

Reduction of Higher Oxides

Sulfur dioxide is also a byproduct in the production of calcium silicate cement, which involves heating CaSO4 with coke and sand:

2 CaSO4 + 2 SiO2 + C → 2 CaSiO3 + 2 SO2 + CO2

This technique generated commercial quantities of sulfuric acid and cement in Whitehaven, England, until the 1970s. The sulphate freed sulfur dioxide gas, which is utilized in the manufacturing of sulfuric acid, when it was combined with shale or marl and roasted. The reaction also created calcium silicate, which is a precursor in the creation of cement.

The action of hot concentrated sulfuric acid on copper turnings creates sulfur dioxide on a laboratory scale.

Cu + 2 H2SO4 → CuSO4 + SO2 + 2 H2O

Reaction of Sulfur Dioxide (SO2)

Chemical Reactions In The Lab

Sulfur dioxide is one of the few acidic yet reducing gases found in nature. Because it’s acidic, it turns damp litmus pink, then white (due to its bleaching effect). It may be detected by bubbling it through a dichromate solution (Cr3+ (aq)), which turns the solution from orange to green. It also has the ability to convert ferric ions into ferrous ions.

In a cheletropic process, sulfur dioxide reacts with specific 1,3-dienes to generate cyclic sulfones. Sulfolane, a key solvent in the petrochemical sector, is synthesized via this process on an industrial scale.

Metal sulfur dioxide complexes are formed when sulfur dioxide binds to metal ions as a ligand, usually when the transition metal is in oxidation state 0 or +1. Many distinct bonding modes (geometries) are documented, although in most cases, the ligand is monodentate and is connected to the metal through sulfur, which can be planar or pyramidal.

Sulfur dioxide operates as a Lewis base employing the lone pair on S as a 1-SO2 (S-bonded planar) ligand. In its 1-SO2 (S-bonded pyramidal) bonding mode with metals, and in its 1:1 adducts with Lewis bases like dimethylacetamide and trimethyl amine, SO2 acts as a Lewis acid. The acid parameters of SO2 for attaching to Lewis bases are EA = 0.51 and EA = 1.56.

Uses of Sulfur Dioxide (SO2)

The manufacturing of sulfuric acid is the most common and prominent usage of sulfur dioxide.

1. Precursor of Sulfuric Acid

Sulfur dioxide is a precursor of sulfuric acid since it is turned into sulfur trioxide and, subsequently, to oleum, which is then converted to sulfuric acid. Sulfur dioxide is created when sulfur reacts with oxygen for this purpose. The contact process is the method of turning sulfur dioxide to sulfuric acid. Every year, many billions of kg are manufactured for this purpose.

2. It’s Used As a Preservative

Because of its antibacterial characteristics and capacity to prevent oxidation, sulfur dioxide is occasionally used as a preservative for dried apricots, dried figs, and other dried fruits in Europe, where it is known as E220.

It acts as a preservative, preserving the fruit’s vibrant look and preventing rotting. It’s also used in the production of sulfur molasses.

The Romans were the first to employ sulfur dioxide in winemaking when they found that burning sulfur candles inside empty wine jars kept them fresh and free of vinegar odor.

It is still a significant component in winemaking, and its concentration is measured in parts per million (ppm). It can be found in amounts of up to 10 mg/L in so-called unsulfurated wine.

It acts as an antibiotic and antioxidant, protecting wine against bacterial spoilage as well as oxidation, which causes browning and the loss of cultivar-specific characteristics. Its antibacterial properties also aid in the reduction of volatile acidity.

Sulfur dioxide also works well as a reluctant. Sulfur dioxide has the ability to decolorize things in the presence of water. It’s a good reducing bleach for papers and other sensitive things like clothing. Normally, the bleaching effect does not last very long.

The reduced dyes are reoxidized by oxygen in the air, which restores the color. Sulfur dioxide is used to detoxify chlorinated wastewater before it is released in municipal wastewater treatment. Free and mixed chlorine are converted to chloride by sulfur dioxide.

3. Sulfur Dioxide Also Works Well As a Reluctant

Sulfur dioxide has the ability to decolorize things in the presence of water. It’s a good reducing bleach for papers and other sensitive things like clothing. Normally, the bleaching effect does not last very long.

4. Roles in Biochemistry and Biomedicine

Both sulfate-reducing organisms and sulfur-oxidizing bacteria create sulfur dioxide or its conjugate base bisulfite as a biological intermediary. Sulfur dioxide’s involvement in mammalian life is not fully known. The Hering–Breuer inflation reflex is abolished when sulfur dioxide suppresses neuronal impulses from the pulmonary stretch receptors.

Endogenous sulfur dioxide is thought to play a key role in regulating cardiac and blood vessel function, and abnormal or deficient sulfur dioxide metabolism has been linked to a variety of cardiovascular diseases, including arterial hypertension, atherosclerosis, pulmonary arterial hypertension, and stenocardia.

Homocysteine levels are higher and endogenous sulfur dioxide levels are lower in children with pulmonary arterial hypertension related to congenital heart disorders than in normal control children.

Furthermore, the degree of pulmonary arterial hypertension was substantially linked with these biochemical markers. According to the authors, homocysteine was identified as a valuable biochemical measure of illness severity, and sulfur dioxide metabolism was identified as a prospective therapeutic target in those individuals.

5. In the Laboratory, As a Reagent and Solvent

Sulfur dioxide is an inert solvent that is commonly used to dissolve highly oxidizing compounds. It’s also employed as a sulfonyl group source in chemical synthesis on occasion. The aryl sulfonyl chloride is produced by treating aryl diazonium salts with sulfur dioxide and cuprous chloride.

6. Imaginative Applications

When used as a refrigerant,

Sulfur dioxide is a promising material for refrigerantssince it is easily condensed and has a high heat of evaporation. Sulfur dioxide was employed as a refrigerant in household freezers before the invention of chlorofluorocarbons.

The Manipulation of the Climate

Climate engineering has advocated injecting sulfur dioxide into the stratosphere. The cooling effect would be comparable to what was witnessed following Mount Pinatubo’s big explosive eruption in 1991. However, this type of geoengineering would have undetermined regional effects on rainfall patterns, such as in monsoon-prone areas.

Sulfur Dioxide (SO2) is Air Pollutant

Sulfur dioxide is a prominent component of the atmosphere, particularly after volcanic eruptions. The quantity of sulfur dioxide released in the United States every year, according to the United States Environmental Protection Agency (EPA), was:

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 severe air contaminant that has serious health consequences. Furthermore, the amount of sulfur dioxide in the atmosphere has an impact on the appropriateness of habitat for plant groups and animal life. Sulfur dioxide emissions are precursors of acid rain and particles in the atmosphere.

Between 1983 and 2002, the United States saw a 33 percent reduction in emissions, thanks primarily to the US EPA’s Acid Rain Program. Flue-gas desulfurization, a process that allows SO2 to be chemically bonded in power plants using sulfur-containing coal or oil, contributed to this improvement.

Control of Sulfur Dioxide (SO2)

To limit sulfur emissions from coal-fired power plants, hundreds of relatively efficient technologies have been developed.

By employing limestone as a bed material in fluidized bed combustion, sulfur may be eliminated from coal during combustion.

Sulfur can also be removed from fuels before they are burned, avoiding the creation of SO2. In refineries, the Claus process is used to create sulfur as a byproduct.

Sulfur has also been removed from gasoline using the Stretford technique. Redox procedures involving iron oxides, such as Lo-Cat or Sulferox, can also be employed.

According to a study, 18 coal-fired power plants in the western Balkans released two-and-a-half times more sulfur dioxide than the EU’s total of 221 coal plants.


Because sulfur dioxide is changed to sulfur trioxide and then to oleum, which is eventually converted to sulfuric acid, it is a precursor of sulfuric acid. When sulfur combines with oxygen for this purpose, sulfur dioxide is produced.

sulfur dioxide, also known as E220 in Europe, is occasionally used as a preservative for dried apricots, dried figs, and other dried fruits due to its antimicrobial properties and ability to prevent oxidation.

In the presence of water, sulfur dioxide has the power to decolorize objects. For papers and other delicate items like textiles, it’s a good reducing bleach. The bleaching effect does not usually endure long.

Frequently Asked Question (FAQs)

The following are some frequently asked questions by people:

Q1. Is supplied poisonous to humans?

According to the EPA’s most recent evaluation of the evidence, sulfur dioxide has a variety of negative effects on the lungs, including wheezing, shortness of breath, chest tightness, and other issues, especially during exercise or physical activity.

Q2. What is the function of sulfur dioxide?

Sulfur dioxide is employed in a variety of fields. Sulfuric acid, paper, and food preservatives are all made with it. The following are some instances of employees who may be exposed to sulfur dioxide: Workers in industries where it is produced as a by-product, such as copper smelting and power plants.

Q3: What is the issue with sulfur dioxide?

The skin and mucous membranes of the eyes, nose, throat, and lungs are irritated by sulfur dioxide.

Q4. Is sulfur dioxide harmful to the environment?

Gaseous SOx can affect trees and plants by destroying leaves and reducing growth at high quantities. Acid rain, caused by SO2 and other sulfur oxides, can destroy delicate ecosystems.

Q5. Is sulfur dioxide bad for your health?

Is sulfur dioxide a cancer-causing gas? The International Agency for Research on Cancer (IARC) decided that it is unknown if sulfur dioxide causes cancer and so classified it as non-classifiable due to a lack of human evidence and inadequate data in animals.

Q6. What’s the best way to get sulfur dioxide out of dried fruit?

The dried fruit must first be thoroughly washed with water to remove the sulfur dioxide. After that, soak the dried fruit for 10 minutes in a combination of lemon juice and water. Drain the dried fruit or raisins, which are a form of dried fruit, on a clean cloth after 10 minutes to remove the water.

Q6. Is it true that SO2 is a bleaching agent?

Sulfur dioxide functions as a transient bleaching agent, removing oxygen through the reduction reaction described above. As a result, sulfur dioxide reduces colorful compounds to make them colorless by removing oxygen.

Q7. Is it safe to ingest sulfur dioxide?

Sulfur dioxide is frequently utilized as a preservative and antioxidant in the food and beverage industries. While it is safe for healthy people when used at appropriate quantities, it can cause asthma in sensitive people when breathed in or swallowed, even at high dilution.

Q8. What effect does sulfur have on the human body?

It is the human body’s Sulfur appears to have antibacterial properties against acne-causing microorganisms. It may also aid in the loosening and shedding of skin. This is said to aid in the treatment of skin disorders like seborrheic dermatitis and acne.

Q9. What is the best way to get rid of sulfur dioxide?

Open windows and vents as soon as possible in any place where sulfur dioxide is present. To absorb liquid sulfur dioxide, use an absorbent medium like clay-based cat litter, soda ash, or dry lime.

Q10. What is the best way to protect oneself against sulfur dioxide?

When vog levels are high, avoid outdoor activities that require heavy breathing.

  • To avoid dehydration, drink lots of water.

  • Smoking and secondhand smoke should be avoided.

  • Prior to a gas inundation, stay inside and close windows and doors.

  • If you’re using an air conditioner, make sure it’s set to recirculate.


Sulfur Dioxide (SO2) has a molar mass of 64.0638 g/mol. sulfur dioxide (IUPAC approved spelling) or sulfur dioxide is a chemical compound with the formula SO 2. (Traditional Commonwealth English). This noxious gas is responsible for the odor of burning matches. It’s a byproduct of copper mining and the combustion of sulfur-bearing fossil fuels, and it’s naturally generated by volcanic activity. sulfur dioxide has a nitric acid-like odor.

Electric utilities, particularly those that burn coal, are responsible for the majority of sulfur dioxide discharged into the atmosphere. Petroleum refineries, cement manufacturing, paper pulp manufacturing, and metal smelting and processing plants are all producers of sulfur dioxide.

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