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Oxoacids of Sulphur

Last Updated : 22 Dec, 2021
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Oxoacids are oxygen-containing acids. Many oxoacids, such as H2SO4, H2SO3, and others, are known to be formed by sulphur. When sulphur is coordinated to oxygen, it forms a tetrahedral structure in oxoacids. Sulfur oxoacids are sulphur, oxygen, and hydrogen-containing chemical compounds. Sulfuric acid is the most well-known and widely utilised in industry. Sulfur contains various oxoacids; however, some of these are only recognised through their salts. The acids that have been described have a variety of structural characteristics.

Sulphuric acid

Sulphuric acid is one of the most common sulphur oxoacids. It is a kind of diprotic acid (it ionises to give two protons). One atom of sulphur is connected to two hydroxyl groups in sulphuric acid, and the remaining two oxygen atoms form pie connections with the sulphur atom. 

As a result, sulfuric acid has tetrahedral geometry. Because the bond length of the sulphur oxygen link is shorter than that of the S-OH bond, oxygen atoms repel OH groups. As a result, the bond angle in a double bond of sulphur and oxygen is greater than the bond angle in a single bond of sulphur and oxygen. It is manufactured industrially by the contact method.

Sulphuric Acid Structure

Properties of Sulphuric Acid

  1. Water dissolves sulphuric acid. When sulfuric acid is mixed with water, it produces a substantial amount of heat as well as a drop in volume. The heat generated while diluting concentrated sulphuric acid has the potential to cause an accident. To minimize accidents, the concentrated acid should always be mixed with water rather than the acid being mixed with water.
  2. It condenses into a constantly boiling mixture.
  3. It emits a pungent odour when exposed to damp air.
  4. When it comes into touch with the skin, it causes serious burns.

Uses of Sulphuric Acid

  1. It is used in the manufacture of fertilisers such as ammonium sulphate, lime superphosphate, and others.
  2. It is used to make colours, explosives, and medications.
  3. It is used to make acids such as HCl, HNO3, and others.
  4. It is utilised in the manufacture of a wide range of other compounds.
  5. It is employed in galvanizing, enamelling, and metallurgical processes.
  6. It’s utilised in the leather business, storage cells, and the petroleum sector, among other things.
  7. It’s a dehydrating agent and a scientific reagent.

Sulphurous acid

Sulphuric acid is a diprotic acid, which means that it ionizes two protons. One sulphur atom is bonded to two hydroxyl groups in sulphurous acid, and one oxygen atom forms a pi bond with the sulphur atom. Sulphur dioxide is dissolved in water to make it. 

Despite the fact that there is no indication of sulphurous acid in the solution, the molecule can be separated in the gaseous phase. Because it is quickly oxidised into sulphuric acid, this acid acts as a potent reducing agent even in the presence of ambient oxygen. As a result, halogens become hydracids, ferric salts become ferrous salts, and so on. It also serves as a bleaching agent.

Sulphurous Acid

Peroxodisulphuric acid

Sulphur in the +6 oxidation state is present in peroxodisulphuric acid. As a result, it is a strong oxidizing agent and a highly explosive substance in nature. Marshall’s acid is the common name for it. It has one peroxide group that forms a bridge between the two sulphur atoms. 

Other than the peroxide group, each sulphur atom is linked to one hydroxyl group (S-OH bond) and two oxygen atoms (S=O bond). We can make it by reacting chlorosulfuric acid with hydrogen peroxide. The following is the reaction:

2ClSO3H + H2O2 → H2S2O8 + 2HCl

Peroxodisulphuric acid

Pyrosulphuric Acid

Pyrosulphuric acid is also referred to as oleum. It has a molecular mass of 178.13 g/mol. It is a colourless, crystalline solid with a melting point of 36°C that is an anhydride of sulphuric acid. It is made by reacting excess sulphur trioxide with sulfuric acid. The reaction is as follows:

H2SO4 + SO3 → H2S2O7

It interacts with bases to generate salts known as pyrosulphates. It is used in the production of explosives and dyes. It is also utilised in the refining of petroleum. It is a potent dehydrating agent that is also corrosive. It can cause skin burns as well as eye discomfort. Long-term exposure can be lethal.

Pyrosulphuric Acid

Thiosulphuric acid

The inorganic substance with the formula H2S2O3 is thiosulfuric acid. It has piqued the curiosity of academics as a simple, easily accessible, labile chemical. It has few practical applications.

Thiosulphuric acid

Dithionic acid

Dithionic acid is diprotic, and salts known as dithionates exist. There have been no discoveries of acid salts. Water rapidly dissolves all dithionates. They are both weak oxidizing and reducing agents. The dithionate ion has the same structure as ethane, but two SO3 groups adopt a nearly eclipsed configuration.

Dithionic acid

Sample Questions

Question 1: Which are the Oxoacids of Sulphur?


Sulfur oxoacids are sulphur, oxygen, and hydrogen-containing chemical compounds. Sulfuric acid is the most well-known and widely utilised in industry.

Question 2: What are the 4 types of oxyacids of chlorine?


Chlorine can be broken down into four types of oxoacids. That is, HOCl (hypochlorous acid), HOClO (chlorous acid), HOClO2 (chloric acid), and HOClO3 (perchloric acid).

Question 3: Where sulphur is found?


Sulfur can be found in its natural state as well as in metal sulphide ores. It can be found in its natural state around volcanoes and hot springs. Sulfur is the tenth most prevalent element, and it may be found in meteorites, the ocean, the earth’s crust, the atmosphere, and almost all plant and animal life.

Question 4: What are oxyacids used for?


As a powerful acid and an oxidising agent, nitric acid is widely utilised in laboratories and chemical industries. The acid is widely used in the production of explosives, dyes, plastics, and drugs. Nitrates are useful fertilisers.

Question 5: What is oxoacids chemistry?


An oxoacid (also known as an oxyacid) is a type of acid that contains oxygen. An oxoacid, to be more technical, is an acid that contains oxygen. consists of at least one other element has one or more hydrogen atoms linked to oxygen

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