What is the formula of sulfur dioxide?

Sulfur dioxide

Sulfur dioxide is a very smelly chemical and is dangerous if not handled properly which can lead to various kinds of problems. This chemical is the primary ingredient that is needed in the preparation of sulfuric acid and is commonly known to be the king of chemicals as it is no doubt the most widely and commonly used chemical in the industrial sector. It is being interacted by people first thing first when they start their vehicles. Sulfur dioxide is a water-soluble gas and is colorless. It is produced due to the burning of Sulphur and it is not inflammable. The sulfur dioxide can further be converted to sulfur trioxide when it is exposed to an environment containing oxygen. This gas is extremely poisonous with a very strong odor. This gas can naturally occur during activities by volcanoes where it is being produced as gas which is of waste. This occurs due to the heating up of materials containing sulfur. Other examples where it can be produced are during the combustion of coal containing sulfuror oil, in the process of smelting of iron, and so on. This is considered a pollutant in most of its emissions as it causes ecological threats.

Formula and Structure of Sulphur Dioxide

It is a bent molecule containing polar covalent bonds. The bonds are present between two oxygen atoms and a sulfur atom. The formula of sulfur dioxide is given as SO₂. The bond is of the order 1.5 and the structure can be obtained using the valence bond theory incorporating the s and p orbitals. The resonance structure is given in the figure below:

Structure of Sulphur Dioxide

Laboratory and Commercial Preparation of Sulphur Dioxide

1. Sulfur dioxide, in labs, is obtained by reacting metallic sulfite (ormetallic bisulfite) with dilute acid.

An example of this is the reaction that takes place between sodium sulfite and sulphuric acid which is diluted which gives off Sulphur dioxide (SO₂).

The reaction is given below:

Na₂SO₃ + H₂SO₄→ Na₂SO₄ + H₂O + SO₂

2. However, commercially it can be obtained by the roasting of sulfide ores which is released as a by-product. The by-product obtained which is in the form of a gas is dried and liquefied followed by storing in steel cylinders.

4FeS₂ (s) + 11O₂ (g) →2Fe₂O₃ (s) + 8SO₂(g)

As discussed earlier this is used in process of converting sulfur, oxygen, and water into sulfuric acid. Also, sulfur dioxide can combine with free oxygen molecules to give SO₃ (sulfur trioxide). This is known as the oxidation of materials containing sulfur which first forms SO₂ followed by the formation of SO₃. This molecule is added to water where it absorbs it forming H₂SO₄ (sulfuric acid). This is mostly used in the industrial sector where SO₂ is used for the preparation of H₂SO₄.

Notes:

Formula	SO₂
Molar mass	64.066 g/mol
IUPAC ID	Sulfur dioxide
Melting point	-72 °C

Uses for Sulfur Dioxide

1. Sulfur dioxide is one of the most widely used compounds in industries and it is the primary ingredient of the commonly used chemical, sulfuric acid. Approximately 180 million tons of SO₂arebeing processed and manufactured each year. The sulfuric acid produced from SO₂ has many applications in most industries like the steel production industries, fertilizers industries, pharmaceutical and medicines industries, paper and plastics industries, and so on. It is also used in fuels, batteries, and has many other applications.
2. It is used for controlling pests where it is used as an ingredient in many pest-controlling products. It is also usedin the preservation of various dried food products. It inhibits the growth of bacteria in dried fruits which helps in prolonging the freshness of the food products. Sulfur dioxide is believed to be a good bleaching agent.
3. It can be used as a disinfectantas well where it can be sprayed on woods, straws, etc. SO₂is also widely used as a fumigating agent for the elimination of insects and other harmful pests.

Impact on Plants

Sulfur dioxide can affect plants in at least two ways:

1. The presence of sulfur dioxide can disrupt the photosynthesis process. SO₂opens the plants’ stomata and also opens leaves causing them to lose water.  The effects of SO2 are different from plant to plant. Some are more sensitive compared to others. The effects can decrease both the quality and quantity of yielded crops.
2. Secondly is its formation of sulfuric acid when it comes in contact with oxygen and water molecules present in the atmosphere.This can further lead to acid rain and smog which is quite dangerous. The moisture formed in clouds gets mixed with SO₃ and produces sulfuric acid rain. The main producers of sulfur dioxide are the manufacturing processes involving the heating of sulfur-containing materials.