Hydrogen Peroxide – Preparation, Properties and Uses
Hydrogen peroxide is a powerful oxidizing agent used in numerous industrial and laboratory processes. Its primary use is the production of paper and pulp, but it can also be used for bleaching, disinfecting, water treatment and other applications. In this article, we shall look at the uses, laboratory preparation and industrial preparation of hydrogen peroxide. We shall explore its history and its various applications, as well as how it is produced on an industrial scale. Whether you are looking to learn more about this chemical compound or to find out how to make it yourself, this article will provide all the information you need.
Properties and Structure of Hydrogen Peroxide
This compound is a molecule composed of two hydrogen atoms and two oxygen atoms. It is a clear, colorless liquid with a slightly bitter taste. Hydrogen peroxide is slightly more dense than water and is soluble in water.
Hydrogen peroxide has many properties that make it useful in a variety of applications. It is an oxidizing agent, meaning that it can accept electrons from other molecules, making them more reactive. This property makes hydrogen peroxide useful as a bleaching agent and disinfectant. It is also a reducing agent, meaning that it can donate electrons to other molecules, making them less reactive. This property makes hydrogen peroxide useful as an antifungal agent and for treating wounds.
The structure of this compound determines its properties. The molecule consists of two oxygen atoms bonded to each other by a single covalent bond. The oxygen atoms are each bonded to a hydrogen atom by a single covalent bond. The structure of the molecule allows it to easily accept or donate electrons, giving it its oxidizing and reducing properties.
Hydrogen peroxide is a strong oxidizing agent that is used in a variety of applications. It can be used to disinfect surfaces, bleaching agent, and as an antiseptic. In the laboratory, hydrogen peroxide can be prepared by the oxidation of water with oxygen gas.
It is one of the most important chemicals in the world. It is used in a wide variety of industries, including:
Paper Industry
Textile industry
Electronics industry
Food and beverage industry
Pharmaceutical industry
In addition to its many industrial uses, hydrogen peroxide is also used in the laboratory for a variety of purposes, including:
– Disinfecting surfaces and equipment
– Bleaching fabrics and paper products
– Removing stains and deposits from glassware and metals
Decomposition of Hydrogen Peroxide
Hydrogen peroxide is a highly unstable molecule, decomposing readily to oxygen and water. The rate of decomposition increases with temperature, concentration and the presence of catalysts. Decomposition is usually catalyzed by transition metal ions, such as iron or copper.
In the absence of a catalyst, hydrogen peroxide decomposes very slowly at room temperature:
2 H2O2 → 2 H2O + O2
The half-life of a 20% solution of hydrogen peroxide at 20 °C is approximately one year.
Hydrogen peroxide is one of the hydrides formed by the combination of hydrogen with oxygen. The other hydride is water. Hydrogen peroxide was first prepared by Thenard by the action of dilute tetraoxosulphate(VI) acid on barium peroxide. He found out that H2O2 contained more oxygen molecule than water, H2O and this discovery prompted him to call it oxygenated water. This liquid occurs in trace amounts in nature. It occurs in dews and in air. It also occurs in water that has been exposed to brilliant sunshine.
Laboratory Preparation of Hydrogen Peroxide
This liquid is prepared in the laboratory by the action of dilute acid on some metallic peroxides. A salt is also produced as a bi-product of the reaction. Most often, barium peroxide is used alongside with dilute tetraoxosulphate(IV) acid. The reason for this is that the barium tetraoxosulphate(VI) produced is insoluble and can readily be filtered off the system.
H2SO4(aq) + BaO2(s) → BaSO4(s) + H2O2(aq)
Industrial Preparation of Hydrogen Peroxide
H2O2 is produced industrially by the oxidation of propan-2-ol with oxygen. The reaction is carried out under slight pressure.
It can also be produced industrially by the oxidation of substituted anthracene-9, 10-diones. The solution of H2O2 obtained can be concentrated by distilling it under reduced pressure. Since this compound is easily decomposed by light, it is stored in dark glass containers or bottles or in aluminium containers. Moreover, a solution of hydrogen peroxide must be kept pure to prevent its catalytic decomposition.
This compound is sold in various concentrations and these concentrations are expressed as its volume-strength which is the number of volumes of oxygen(measured at s.t.p), that is liberated by one volume of hydrogen peroxide on heating. This means that 1cm3 of a 10-volume solution of H2O2 would liberate 10cm3 of oxygen(at s.t.p) when it decomposes completely. This compound is usually sold at concentration levels of 10-volume, 20-volume and 30-volume.
Uses of Hydrogen Peroxide
Some of the uses of H2O2 include:
(1) One of the most important uses of hydrogen peroxide in medicine is its use as an antiseptic.
(2) Liquid hydrogen peroxide provides oxygen for the burning of fuel in space rockets. It is also used in the burning of diesel oil in the engines of submerged submarines.
(3) This compound is used in bleaching delicate materials such as silk, wood pulp, wool, human hair and feathers. This use is particularly needed especially when chlorine or sulphur(IV) oxide could cause damage to the material when used for bleaching.
(4) It is used in the manufacture of chemical compounds such as sodium dioxochlorate(III) and some organic peroxides which are used in initiating polymerization reactions.
(5) Mixtures such as white lead(II) paints that contain lead(II) tetraoxocarbonate(IV) blackens when exposed to atmospheric hydrogen sulphide because the lead(II) compounds present are readily converted into lead(II) sulphide. Therefore treatment with hydrogen peroxide oxidizes the lead(II) sulphide to lead(II) tetraoxosulphate(VI), thereby restoring the original white color.
PbS(s) + 4H2O2(aq) → PbSO4 + 4H2O(l)
Physical Properties of Hydrogen Peroxide
(i) Hydrogen peroxide is a pale blue syrup liquid.
(ii) This compound boils and decomposes at 1500C and freezes at about -0.90C
(iii) Hydrogen peroxide dissolves in water to give a very weak acidic solution.
Chemical Properties of Hydrogen Peroxide
(i) Decomposition: As mentioned above,it decomposes to form water and oxygen when exposed to air. This decomposition is exothermic and is accelerated by heating, addition of alkalis and the introduction of finely divided metals such as platinum, gold and manganese(IV) oxide which acts as a catalyst.
2H2O2(l) → 2H2O(l) + O2(g)
Mineral acids and propane-1,2,3-triol inhibits the decomposition of hydrogen peroxide. These compounds are often added to commercial hydrogen peroxide to minimize its decomposition.
(ii) Hydrogen Peroxide as an Oxidizing Agent: Itis a strong oxidizing agent as it can readily donate oxygen or accept electrons. In this process, it is reduced to water. Its oxidative property can be seen in its reaction with potassium iodide solution that has been acidified with tetraoxosulphate(VI) acid, where it liberates iodine. The tetraoxosulphate(VI) acid first reacts with the iodide to form iodic acid, HI, which is subsequently oxidized by hydrogen peroxide to liberate iodine. The oxidation process carried out by hydrogen peroxide is done by its acceptance of electrons from the iodide ion, and itself being reduced to water.
2KI(aq) + H2O(aq) +H2SO4(aq) →K2SO4(aq) + 2H2O(l) +I2(aq)
(iii) Hydrogen Peroxide as a Reducing Agent: This compound can also behave like a reducing agent when it reacts with more powerful oxidizing agents by either donating electrons or accepting oxygen. The reduction process leads to hydrogen peroxide itself being converted to gaseous oxygen. For instance, hydrogen peroxide reduces acidified potassium tetraoxomanganate(VII) solution making it colorless because the purple tetraoxomanganate(VII) ion is changed in to the pale pink manganese(II) ion.
2KMnO4(aq) + 3H2SO4(aq) + 5H2O2(aq) → K2SO4(aq) + 2MnSO4(aq) 8H2O(l) + 5O2(g)
This chemical compound can equally reduce chlorine to hydrochloric acid and silver oxide to the metal.
Cl2(g) + H2O2(aq) → 2HCl(aq) + O2
Ag2O(s) + H2O2(aq) → 2Ag(s) + H2O(l) O2
Conclusion
Hydrogen peroxide is widely used in both laboratory and industrial settings. It can be easily prepared from oxygen and water, or through various catalytic reactions. In the laboratory it’s a versatile reagent with many uses, while in industry it’s often used as an oxidizing agent or bleaching agent. Its safety record makes it suitable for both laboratory and large-scale industrial production of other chemicals. With its multitude of uses and ease of preparation, hydrogen peroxide is a beneficial chemical compound that has become an essential industrial product around the world.
