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Chlorous Acid

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Chlorous Acid is an inorganic compound that is acidic in nature. It is a weak acid and its chemical formula is HClO2. It is an oxoacid of chlorine and the oxidation state of chlorine in Chlorous Acid is +3. In its pure form, Chlorous Acid is highly stable and it disproportinates to Hypochlorous Acid and Chloric Acid.

In this article, we will learn about, Chlorous Acid, Chemical Formula of Chlorous Acid, Structure of Chlorous Acid, and others in detail.

What is Chlorous Acid?

Chlorous acid is an inorganic compound, it is a weak acid. In this acid, Chlorine has a +3 oxidation state. The pure substance present in chlorous acid is unstable and it disproportionates to Hypochlorous Acid and Chloric Acid. This acid has a conjugate base called Chlorite and it is a stable compound. Chlorous acid consists of one Chlorine atom, one Hydrogen atom, and two Oxygen atoms.

Chlorous Acid formula

The chemical formula of Chlorous acid is HClO2. It contains One Chlorine Atom, One Hydrogen Atom and Two Oxygen Atom. It is an oxoacid of Chlorine and the oxidation state of Chlorine in Chlorous Acid is +3.

Chlorous Acid Preparation

Chlorous Acid is prepared when Barium Chlorite reacts with dilute sulfuric acid. The chemical reaction for the same is added below,

Ba(ClO2)2 + H2SO4 → BaSO4 + 2 HClO2

Chlorous Acid is also prepared when Lead Chlorite reacts with dilute sulfuric acid. The chemical reaction for the same is added below,

Pb(ClO2)2 + H2SO4 → PbSO4 + 2 HClO2

Structure of Chlorous Acid

Chemical formula of Chlorous acid is HClO2 and molar weight of Chlorous acid is 68.46g/mol. The formation of the structure takes place by one proton H+, whose attachment is to a chlorite anion ClO2-. The structure of Chlorous Acid is shown in the image added below, 

Structure of Chlorous Acid

Physical Properties of Chlorous Acid

The physical properties of Chlorous Acid is,

  • Molecular weight of Chlorous Acid is 68.46 g/mol.
  • Chlorous acid is a colorless liquid, without a characteristic aroma. 
  • This acid acts as a strong oxidizing agent. 
  • Chlorous acid is also incompatible with reducing agents and alkalis.
  •  It is commonly used as a mouthwash for the reduction of plaque.
  • Chlorous acid has a 1.96 pKa and its determination takes place as the stability of the conjugate base of an acid is determined. The value of 1.96 pKa indicates that the conjugated base chlorite ClO2- is stable.  
  • The boiling point of chlorous acid is 502.07°C.

Chemical Properties of Chlorous Acid

Various chemical properties of the Chlorous Acid are added below,

  • Chlorous acid is unstable and it reacts to gives results in the formation of  chloric acid and hypochlorous acid, one of them comes due to the reduction of Cl3+ to Cl1+, while the second is from the oxidation of Cl3+ to Cl5+

2HClO2 → HClO + HClO3

  • Chlorous acid acts as a powerful oxidizing agent.
  • Chlorine is the only oxoacids of halogen that gives the formation of an isolable acid of formula HXO2.

Uses of Chlorous Acid

The uses of Chlorous Acid are,

  • Chlorous acid acts as a strong oxidizing agent.
  • Chlorous acid is incompatible with reducing agents and alkalis. 
  • It is commonly used as a mouthwash for the reduction of plaque. 
  • The conjugated base chlorite is used as the sodium salt. 
  • This salt of Chlorous Acid is used in various industrial processes such as production of Chlorine Dioxide.

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Sample Questions on Chlorous Acid

Q1: What is Chlorous Acid and its Formula?

Answer:

Chlorous acid  is an inorganic compound, it is a weak acid. In this acid Chlorine has +3 oxidation state. The chemical formula of Chlorous Acid is HClO2.

Q2:  What are the Health Hazards of Chlorous Acid?

Answer:  

Chlorous acid can be very harmful if someone swallows or inhales it. It can cause severe damage to mucous, skin and eyes. If someone wears contact lenses and chlorous acid comes into contact with the eyes, then one must immediately take the lens off and wash the eyes with water for 15 minutes by keeping the eyelids open.  Also, one must avoid the use of any ointment. In case this acid comes into contact with the clothing, then one must quickly remove the clothing and take a bath immediately. 

Q3: Is Chlorous Acid a liquid?

Answer: 

Yes, Chlorous Acid is a colorless liquid.

Q4: How is Chlorous Acid Formed?

Answer: 

HClO2 is prepared by reacting Barium Chlorite or Lead Chlorite with dilute Sulfuric Acid. The reaction for the same are added below,

Ba(ClO2)2 + H2SO4 → BaSO4 + 2 HClO2

Pb(ClO2)2 + H2SO4 → PbSO4 + 2 HClO2

Q5: What type of compound is Chlorous acid?

Answer:

Chlorous acid is an inorganic acid with chemical formula HClO2. In this acid, Chlorine has oxidation state of  +3.

Q6: What is the Anion for Chlorous acid?

Answer:

Anion of Chlorous acid is ClO2- and the anion name Chlorite Acid. It has one chlorine atom and 2 oxygen atoms.

FAQs on Chlorous Acid

1. What is Another name for Chlorous Acid?

The other name of Chlorous Acid is Hydrogen Chlorite.

2. What is the Formula for Chlorous Acid?

The Chemical Formula for Chlorous Acid is HClO2.

3. What is HClO2 called?

HClO2 is called Chlorous Acid. It is an oxocid of Chlorine.

4. What is Molecular Weight of Chlorous Acid?

The molecular weight of Chlorous Acid is 68.46 g/mol.

5. What is Conjugate Base of Chlorous Acid?

The conjugate base of Chlorous Acid (HClO2) is called Chlorite Ion. The chemical formula of Chlorite ion is (ClO2-).

6. What is Chlorous Acid Used For?

Chlorous Acid is a weak acid and is commonly used in mouthwashes. Its conjugate base is used as Sodium Salt.



Last Updated : 19 Dec, 2023
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