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Sulfurous Acid Formula: Structure, Properties, Uses, Reactions

The basics of sulfurous acid formula (H2SO3). Sulphurous acid has the formula, with two hydrogen atoms, three oxygen atoms, and one sulfur atom in the molecule. Find out about its simple structure and essential characteristics, making chemistry easy to grasp.
authorImageRanvijay Singh29 Sept, 2023
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Sulfurous Acid Formula

It is defined as a chemical compound with the formula H 2 SO 3 , Sulfurous Acid is also known as Sulfur dioxide solution or trioxosulfuric acid. Acting as an intermediate species that contributes to acid rain, it is identifiable by its pungent odor of burning sulfur and corrosive properties towards metals and tissue. As a sulfur oxoacid and the conjugate acid of hydrogen sulfite, it can also be described as a colorless liquid and a tautomer of sulfonic acid.

Molecular Formula of Sulfuric Acid

The acid's chemical structure shows that the sulfur atom is in the center, and three oxygen atoms are connected by a single bond and a double bond to form the molecule. A single bond connects the two hydrogen atoms to the oxygen atoms. The sulfurous acid structural formula is normally written as:

Molecular Formula of Sulfuric Acid

Sulfurous Acid Chemical Formula

Sulphurous acid has the formula H 2 SO 3 , with two hydrogen atoms, three oxygen atoms, and one sulfur atom in the molecule.

Formula H 2 SO 3
Molar Mass 82.07 g/mol
Density 1.03 g/mL
Boiling Point -60 °C

Properties of Sulfurous Acid – H 2 SO 3

H 2 SO 3 Sulfurous acid
The molecular weight of H2SO3 82.07 g/mol
No. of hydrogen bond acceptor 4
Monoisotopic mass of Sulfurous Acid 81.97 g/mol
No. of hydrogen bond donor 2
Sulfurous Acid Vapor Pressure Its vapor pressure is 1740 kPa at about 21 °C.
Sulfurous Acid Acidity On the pH scale, sulphurous acid has a pH of 1.5. It's not a very weak acid, but it's also not a particularly powerful acid.

Also Check – Atomic Mass Formula

Sulfurous Acid - A Reducing Agent or Oxidizing Agent

Sulfurous acid, or sulfurous acid, has the chemical formula H 2 SO 3 . While no evidence exists in a solution, it has been detected in its gaseous form. The conjugate bases of this elusive acid are common anions such as bisulfite (or hydrogen sulfite) and sulfite. A weak and unstable acid is formed when sulfur dioxide dissolves in water. The compound's presence in a solution cannot be fully explained but has been observed in its gaseous phase. In addition to being a reducing agent, it also acts as a bleaching agent. Due to its only forming in aqueous solutions, it cannot be isolated in its pure state.

Reasons Behind Some of the Acids being Oxidizing and Some Non-oxidizing

The Bronsted Lowry acids, known as proton donors, are oxidizing agents because they reduce H+ to H2 gas. However, oxidizing solid acids, such as sulphuric acid (H 2 SO 4 ), nitric acid (HNO 3 ), chromic acid (H 2 CrO 4 or H 2 Cr 2 O 7 ), chloric acid (HClO 3 ) and perchloric acid (HClO 4 ), contain anionic forms of oxygen. In contrast, phosphoric acid is a weak oxidizing acid due to its low affinity for oxygen compounds.

Also Check – Elevation of Boiling Point Formula

Reactions of Sulfurous Acid

According to SO 2 Raman spectra solution, it represents that the signal intensities are consistent with the equilibrium given as below: SO 2 + H 2 O ⇌ HSO 3 + H + where pK a = 1.81 and K a = 1.54×10 −2 .

H 2 SO 3 Uses (Sulfurous Acid)

In industry, sulfurous acid is used as a reducing agent, intermediate, and disinfectant. It is also used in the manufacture of paper products.

Also Read – Malic Acid Formula

Health Hazards

Ingesting or inhaling sulfurous acid solution or skin contact causes a severe injury that can result in death. It is corrosive, non-combustible, and toxic. In its molten state, sulfurous acid can cause severe eye and skin burns. As a result, skin contact with this compound is not recommended. As well as releasing toxic, irritating, and corrosive gases, sulfurous acid also causes various health effects.

Chronic Health Effects

Chronic (long-term) health effects may occur months or years after exposure to sulfurous acid:

According to the New Jersey Department of Health & Senior Services, sulfurous acid has not been tested for its ability to cause cancer in animals.

Sulfurous acid compound has not been tested for its reproductive effects.

Sulfurous acid can also irritate the lungs, causing bronchitis with phlegm, cough, and/or shortness of breath due to repeated exposure.

Sulfurous Acid Formula FAQs

Q1. What is the formula for sulfurous acid?

Ans. The formula for sulfurous acid is H2SO3. It is a weak diprotic acid that can donate two protons to water.

Q2. How is sulfurous acid formed?

Ans. Sulfurous acid is formed when sulfur dioxide (SO2) dissolves in water. SO2 is a gas that is produced by the combustion of sulfur-containing fuels, such as coal and oil.

Q3. What are the properties of sulfurous acid?

Ans. Sulfurous acid is a clear, colorless liquid with a pungent odor. It is a weak acid, with a pH of around 2 at room temperature. Sulfurous acid is a good oxidizing agent and can reduce other chemicals.

Q4. What are the uses of sulfurous acid?

Ans. Sulfurous acid is used in a variety of applications, including: Food and beverage industry: Sulfurous acid is used as a preservative in food and beverages, such as wine, beer, and fruit juices. It can also be used to bleach flour and sugar. Water treatment: Sulfurous acid is used to remove chlorine from drinking water. It is also used to disinfect wastewater. Paper industry: Sulfurous acid is used in the production of paper and pulp. Textile industry: Sulfurous acid is used to bleach and dye textiles.

Q5. Is sulfurous acid dangerous?

Ans, Sulfurous acid can be dangerous if it is inhaled or ingested. Inhalation of sulfurous acid can cause coughing, wheezing, and shortness of breath. Ingestion of sulfurous acid can cause nausea, vomiting, and diarrhea. In severe cases, sulfurous acid poisoning can lead to death.
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