How to make Hydrogen peroxide? Properties and Uses

Thenard first created Hydrogen Peroxide H₂O₂ in 1818 by the action of dilute Hydrochloric on Barium peroxide.

Hydrogen Peroxide(H₂O₂)is found in a very small amount of rainwater and the atmosphere.

Structure of Hydrogen Peroxide:

Thenard found that if 17 parts of H₂O₂ are decomposed, by weight, 8 parts of oxygen and 9 parts of water are obtained. Based on this, its proportional formula is HO. Its vapor density is 17 so its weight is 34. Thus its formula is H₂O₂.

According to Kingjet, it is an oxidized product of water and its composition is the formula I.

According to Boyer, it is reduced production of oxygen and its structure is formula II.

Equilibrium Mixture view:

H₂O₂ is a tautomeric mixture of the following two formulas based on evidence in favor of the sources of Kingjet and boyer. At normal temperature, H₂O₂ remains in this mixture, mainly in the form of formula II.

With the help of an x-ray, it has been found that its four atoms do not exist in one place. And its structure is like an open book.

According to Abrahams, the angle between H – O bond and O – O bond is 101.9° and the length of O – O bond and O – H bond is 1.49A° and 0.97A° respectively. There is an angle of 90.2° between the hydrogen atoms.

Preparation Method:

The following are the methods of making H₂O₂.

Sodium peroxide:

In the laboratory, it is made by the action of dilute H₂SO₄ on sodium peroxide.

In a flask, sodium peroxide is slowly added to the solution of dilute H₂SO₄.H₂O₂ is formed by the reaction. Who lives in the solution. Crystals of sodium sulfate(Na₂SO₄.10H₂O) are obtained upon cooling the obtained mixture. Sodium sulfate is also called Glauber Salt.

The Glauber filters the salt and separates it. A 20% solution of H₂O₂ is obtained in the filtrate. 20% solutions of H₂O₂ are also called Perhydrol.

Na₂O₂ + H₂SO₄ → Na₂SO₄ + H₂O₂

Sodium peroxide

Hydrogen Peroxide is obtained from the action of cold water such as ice on sodium peroxide.

Na₂O₂ + H₂O → 2NaOH + H₂O₂

Barium peroxide

Barium peroxide paste contains ice-cooled dilute sulfuric or phosphoric acid. The received precipitate is filtered and separated.

BaO₂ + H₂SO₄ → BaSO₄ + H₂O

3BaO₂ + 2H₃PO₄ → Ba₃(PO₄)₂ + 3H₂O₂

In this method, a hard surface is formed in the flask due to the formation of insoluble Barium sulfate or Barium phosphate. In which this reaction is carried out. This causes the reaction to slow down. This is a drawback to this method.

Merck’s Method

Barium peroxide is carried in cold water and carbon dioxide gas flows into the solution. By releasing carbon dioxide, barium carbonate precipitate is obtained which is separated. H₂O₂ remains in the solution.

BaO₂ + H₂O + CO₂ → BaCO₃ + H₂O₂

Hydrated barium peroxide

H₂O₂ is obtained when hydrated barium peroxide reacts with dilute sulfuric acid. Hydrated barium peroxide (BaO₂.8H₂O) reacts readily with sulfuric acid and the reaction does not slow down due to the formation of insoluble barium sulfate in this method.

BaO₂.8H₂O + H₂SO₄ → BaSO₄ + H₂O₂ + 8H₂O

Auto-Oxidation Method

This is the modern method of making Hydrogen peroxide in large quantities. In this, 2-Ethyl-anthraquinone is dissolved in an organic solvent and it is reduced to hydrogen in the presence of Pd. The 2-Ethyl-anthraquinone derived from this action changes again to 2-Ethyl-anthraquinone. And H₂O₂ is obtained.

Perdisulphuric Acid(H₂S₂O₈)

The industrial manufacture of H₂O₂ can be achieved by steam distillation at a low pressure of Perdisulphuric Acid. About 30% solution of H₂O₂ is obtained by this method.

Electrolytic Process

In this method, ammonium sulfate and dilute sulfuric acid solution are electrolytic. In electrolytic, hydrogen is obtained at the cathode and Ammonium persulfate ((NH₄)₂S₂O₈) at the anode.

(NH₄)₂S₂O₈ + H₂SO₄ → 2NH₄HSO₄

NH₄HSO₄ → NH₄SO₄^– + H⁺

H⁺ + e → H                                                                Cathode

2H → H₂

2NH₄SO₄^– – 2e → (NH₄)₂S₂O₈                                     Anode

H₂O₂ is obtained by distillation of Ammonium persulfate with dilute sulfuric acid at low pressure.

(NH₄)₂S₂O₈ + H₂SO₄ → H₂S₂O₈ + (NH₄)₂SO₄

H₂S₂O₈ +2H₂O → 2H₂SO₄ + H₂O₂

• Ammonia Formula || why ammonia is toxic || Ammonia Poisoning
• Why Ozone Layer is Important || Ozone Layer Depletion
• What is the Concentration of solution || How Concentration Affects Reaction
• Why Carbon Cycle is Important || How it Works
• Haloalkanes and Haloarenes NCERT Solutions || Haloalkane Structure
• Carbon Dioxide Cycle and Formula || How Carbon Dioxide is Produced

Pure H₂O₂ is a colorless odorless thick and transparent fluid. In large amounts, its color appears to be light blue.

Its boiling point is 151⁰C and the freezing point is -0.89⁰C. It rapidly decomposes at its boiling point. Hence its distillation is done at low pressure. Its boiling point is 68⁰C at 26mm pressure.

Its relative density is 1.4694 at 0⁰C and its relative density at 25⁰C is 1.64.

It is soluble in water, ether and alcohol.

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Uses of Hydrogen Peroxide

• It is used in bleaching hair, wool, etc. as bleaching.
• Being antiseptic, it is used to clean wounds, ears, teeth etc.
• It is used as propellant in rocket.
• As an oxidizer
• H₂O₂ is used to make hair color golden.
• It is used to prevent many substances like milk wine etc. from rotting.
• Used in retrieving the colors of old paintings of oil-dyed dyes.