Hypochlorous Acid: Properties, Preparation, Reactions & Uses

Hypochlorous Acid is a weak acid which is formed when chlorine dissolves in the water. The chlorine ions are partially dissociated into hypochlorite ions. Hypochlorous Acid is additionally known as Chlorine Hydroxide or even as a Hydrogen Hypochlorite.

• The chemical formula of Hypochlorous Acid is HOCl. 
• It is also referred to as Oxyacid of Chlorine.
• The acid is comprised of monovalent chlorine that acts as a reducing agent or an oxidizing agent.
• A French chemist named Antoine Jerome Ballard discovered hypochlorous acid in the year 1834.
• One unique feature of this acid is that it is an unstable acid.
• It functions as a human metabolite. 
• It belongs to the family of reactive oxygen species.
• Hypochlorous Acid is also a conjugate acid of a hypochlorite.

Read More: Modern Periodic table

Key Terms: Hypochlorous Acid, Chlorine Hydroxide, Hydrogen Hypochlorite, Acid, Chlorine, Reducing agent, Oxidizing agent, Conjugate Acid, Bleach Sodium Hydroxide 

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Properties of Hypochlorous Acid

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The properties of Hypochlorous Acid are as follows:

Physical Properties of Hypochlorous Acid

The physical properties of Hypochlorous Acid are as follows:

• Hypochlorous Acid is found in an aqueous solution.
• It is basically colourless in nature.
• The precise estimation of its physical properties is difficult as they vary as per the concentration of solution.

Hypochlorous Acid

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Chemical Properties of Hypochlorous Acid

The chemical properties of Hypochlorous Acid are as follows:

• Hypochlorous Acid is a strong oxidizer.
• It can form various types of explosives.
• Hypochlorous Acid is not a strong acid. Hence, it can be fractionally segregated into H+ and hydrochloride ions (OCI-).
• On reacting with bases, it forms hypochlorite salts.

Read More: Aqua Regia

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Preparation of Hypochlorous Acid

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When the Hypochlorous Acid’s aqueous salts (like sodium hypochlorite) in the presence of commercial bleach solution are mixed with acids, the resultant reaction leads to the formation of chlorine gas. 

• Liquefying chlorine gas mixed into basic water solutions such as sodium hydroxide will create hypochlorite bleaches. 
• Acid can also be produced by mixing water with Dichloride Monoxide.
• Hypochlorous Acid undergoes a readily reversible equilibrium reaction with anhydride.
• It is not feasible to produce the Anhydrous Hypochlorite Acid.
• The process of exothermic decomposition into oxygen and hydrochloric acid becomes fast in the presence of light.
• The transition metal oxides of copper, nickel and cobalt are formed.

2 HOCl + Cl₂O + H₂O K (at 0 °C) = 3.55 10⁻³ dm³ mol⁻¹

Hypochlorous Acid

Read Also: Group 15 Elements

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Occurrence of Hypochlorous Acid

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The details about the occurrence of hypochlorous acid are as follows:

• Hypochlorous Acid is commonly found in the human body.
• The acid is produced by the immune system of the human body to fight against the infections.
• It fights against a wide variety of microorganisms.

Read More: Transition Metals

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Chemical Reactions of Hypochlorous Acid

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The chemical reactions involved with Hypochlorous Acid are as follows:

• Hypochlorous Acid gets segregated into the anion hypochlorite Cl^- in an aqueous solution.

HOCl → ClO⁻ + H⁺

• One of the best-known hypochlorite is NaClO, the active substance in bleach.
• When provided the standard conditions HOCl (Hypochlorous Acid) is more powerful oxidant than chlorine.

2HOCl(aq) + 2H⁺ + 2e⁻ → Cl₂(g) + 2H₂O

• Acid reacts with HCl and forms Chlorine gas a resultant product.

HOCl + HCl → H₂O + Cl₂

• It can also react with organic amines, forming n-chloramines.

NH₃ + HClO → NH₂Cl + H₂O

Read More: Covalent Bonds

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Uses of Hypochlorous Acid

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Various uses of Hypochlorous Acid are as follows:

• Alkenes are converted to Chlorohydrin using Hypochlorous Acid
• It is a very effective sanitizing agent and is used as a cleansing agent for skin in cosmetics. 
• It is used to make products such as bleaches, disinfectants, creams, and serums.
• The antimicrobial properties of HOCl make it useful for fighting with skin infections and acne. 
• Due to its anti-inflammatory nature, it is used to treat issues such as Eczema, Rosacea and Psoriasis.
• In hospitals, HOCl is often used as a disinfectant and also as an irritant during surgery.
• SARS-CoV-2, the virus responsible for Covid-19, can be treated with HOCl. 
• It provides a solution to issues such as irritation from colour treatments or skin conditions such as Psoriasis.
• It is used as a piece of equipment in marine sanitation by converting seawater to HOCl.
• It’s also used to treat a wide variety of infections in both pets and people.

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Things to Remember

• Hypochlorous acid is also known as Chlorine Hydroxide or Hydrogen Hypochlorite.
• The chemical formula of Hypochlorous acid is HOCl.
• The molecular Weight of Hypochlorous acid is 52.457 g/mol.
• Hypochlorous acid fights with acne and skin infections.
• In mammals, it is naturally found in their white blood cells.
• We can simply spray Hypochlorous acid into our eyes as it is non-toxic.

Read More: Dioxygen