Oxides and Oxoacids of Halogens: Definition, Concept and Uses

Imagine that you are in camp and need to light a fire. You have struck the match, and after a moment, its head ignites, providing you with that small but necessary flame. This simple action will probably introduce you to a very interesting field of halogen and their oxoacids. The compounds contained in this head of the match, chlorine-based oxoacids, make this procedure of complete combustion.

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This Story also Contains

1. Oxoacids of Halogens
2. Miscellaneous Elements and Forms of Oxoacids of Halogens
3. Relevance and Applications of Oxoacids of Halogens
4. Some Solved Examples
5. Summary

Oxoacids of Halogens

Oxoacids of halogens are such acids that contain Hydrogen, oxygen, and halogen atoms. The general formula for such acids is, where represent a halogen. These halogens are fluorine, chlorine, bromine, and iodine except astatine since it is highly radioactive and is a rarity. Their nature and strength vary to a great extent in a group.

For example, hypochlorous acid, chlorous acid, chloric acid, and perchloric acid are some examples of oxoacids of chlorine where the oxidation state of chlorine is +1, +3, +5, and +7 respectively. Such acids can form the basis for a number of chemical reactions and applications like disinfection, bleaching, and even medicine.

Due to high electronegativity and small size, fluorine forms only one oxoacid, HOF known as fluoric (I) acid or hypofluorous acid. The other halogens form several oxoacids. Most of them cannot be isolated in a pure state. They are stable only in aqueous solutions or in the form of their salts. The oxoacids of halogens are given in the Table below and their structures are given in the figure below.

Miscellaneous Elements and Forms of Oxoacids of Halogens

Physical Properties of Group 13-1

Some of their physical properties are defined with respect to state, color, and solubility; most oxoacids of halogens are colorless and in the state of aqueous solution. They generally act as strong oxidizers whose strength would increase with an increase in the number of oxygen atoms attached to the halogen. For example, perchloric acid is reportedly one of the strongest acids known for the reason that chlorine is at a high state of oxidation, HClO₄.

Group 13 – 2: Physical Properties

It is the oxoacids of the halogens which have special chemical properties. Hypohalous acids, such as hypochlorous acid, and HClO, are weak acids but strong disinfectants. Also, these acids become less stable with an increase in the atomic number of the halogen; that is, iodic acids are less stable than chloric acids. These different oxidation states develop an enormous effect on reactivity and the application of the acid—from gentle disinfection, where only a general disinfectant might be required, to strong oxidants for use in synthesis.

Relevance and Applications of Oxoacids of Halogens

The oxoacids of halogens find application/are important in various aspects. Hypochlorous acid is used as a disinfectant in household bleaches and water treatment to make the water safe for drinking in everyday life. Chloric acid shows strong oxidizing properties; hence it is applied in producing explosives and matches. These acids are the fulcrum of academic research into redox reactions and halogen chemistry. For example, perchloric acid is a strong acid used to function in analytical chemistry for use in titration procedures. The job that hypochlorous acid does in the immune system by helping white blood cells break up disease-causing organisms gives a hint of the great exploitation of these compounds in health and disease management.

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Some Solved Examples

Example 1
Question: The number of Cl=O bonds in perchloric acid is ______

1. 1

2. 2

3. 3 (Correct)

4. 4

Solution:
Perchloric acid (HClO₄) has three Cl=O bonds.

Therefore, the correct answer is 3.

Example 2

Question: Among the following oxoacids, the correct decreasing order of acid strength is:
1. (HOCl>HClO₂>HClO₃>HClO₄)
2. (HClO₄>HOCl>HClO₂>HClO₃)
3. (HClO₄>HClO₃>HClO₂>HOCl)
4. (HClO₂>HClO₄>HClO₃>HOCl)

Solution:
When considering the structure of the conjugate bases of each oxyacid of chlorine, we find that (ClO₄⁻) is the most stable due to greater delocalization of the negative charge. The extent of this delocalization decreases as the number of doubly bonded oxygen atoms decreases on the chlorine center.

Therefore, the order of acidic strength is:

(HClO₄>HClO₃>HClO₂>HOCl)

Hence, the correct answer is option 3.

Example 3
Question: Given below are two statements: one is labeled as Assertion A and the other is labeled as Reason R.

Assertion A: Fluorine forms one oxoacid.

Reason R: Fluorine has the smallest size among all halogens and is highly electronegative.

In light of the above statements, choose the most appropriate answer from the options given below:
1. Both A and R are correct, and R is the correct explanation of A.
2. Both A and R are correct, but R is NOT the correct explanation of A.
3. A is correct, but R is not correct.
4. A is not correct, but R is correct.

Solution:
Fluorine forms only one oxoacid, HOF (fluoric (I) acid or hypofluorous acid). Higher oxoacids are not formed because fluorine is smaller in size and highly electronegative.

Thus, both Assertion (A) and Reason (R) are correct, and (R) correctly explains (A).

Hence, the correct answer is option 1.

Summary

The oxoacid halogens are very vital chemical elements applied industrially, domestically, and biologically. The article has, therefore, been able to highlight the definitions and explanations of those acids, their types, some of their physical properties, and their relation and applications in real life and academics. From making sure that people drink clean water to facilitating complex chemical syntheses, the oxoacids of halogens never cease to amaze researchers when it comes to their utility in different fields.