A Complete Guide to Hydrogen Peroxide

In our Complete Guide to Hydrogen Peroxide, we’ll look in detail at what it is, how it’s made, its uses, hazards, benefits and specifications. You can also find further information on hydrogen peroxide and related reading material in the links at the bottom of this page, and of course you can buy hydrogen peroxide in various concentrations from ReAgent, one of the UK’s leading hydrogen peroxide suppliers.

What Is Hydrogen Peroxide?


As a brief overview, the physical and chemical properties of hydrogen peroxide include:

  • Appearance: Liquid
  • Colour: Colourless (or pale blue in a very concentrated form)
  • Odour: Odourless
  • Formula: H2O2
  • Boiling point (degrees Celsius): 108
  • Melting point (degrees Celsius): Approx. -33
  • Solubility: Miscible with water

A Complete Guide to Hydrogen Peroxide - hydrogen peroxide is a clear, odourless liquid

But this doesn’t tell the whole story. Hydrogen peroxide is the simplest peroxide; a peroxide being a chemical compound with an oxygen-oxygen single bond. With a slightly higher viscosity than water, it is an unstable compound that decomposes when exposed to light.

In fact, if hydrogen peroxide is heated to its boiling point, it can go through thermal decomposition and may become explosive. This instability means that hydrogen peroxide is usually mixed with a stabiliser to form a weaker acid solution.

H2O2 is also a naturally-occurring chemical compound that can be found in biological systems including humans and animals, fresh and sea water, and in the atmosphere. In humans and animals, hydrogen peroxide is the byproduct of a biochemical process and is rapidly decomposed by the body due to its toxicity. In water, hydrogen peroxide is the byproduct of natural catalytic reactions.

Grades of Hydrogen Peroxide

Hydrogen peroxide comes in various grades, or levels of concentration, depending on its end use.

  • 3% hydrogen peroxide is sold for domestic use
  • 6-10% hydrogen peroxide is used to bleach hair
  • 35% or ‘food grade’ hydrogen peroxide is used as a cleaning agent (don’t be fooled by the name, ‘food grade’ definitely doesn’t mean you should drink it!)
  • Up to 90% hydrogen peroxide is in industry

A Short History of Hydrogen Peroxide

In 1799, Prussian scientist Alexander von Humboldt (who, as an aside, was also a geographer, naturalist, explorer, philosopher, and polymath – an all-round busy genius) made the first synthetic peroxide. This was barium peroxide and was produced as a byproduct of von Humboldt’s experiments to decompose air.

Almost twenty years later, French chemist Louis Jacques Thénard used barium peroxide to make ‘eau oxygénée’, or oxygenated water. This later became known as hydrogen peroxide. Through the nineteenth century, chemists improved the methods and processes used to produce hydrogen peroxide. However, the first person to produce pure hydrogen peroxide was German chemist Richard Wolffenstein, who in 1894 used vacuum distillation to make H2O2.

It wasn’t until the mid-twentieth century that a way was found to produce hydrogen peroxide on an industrial scale.  

Hydrogen Peroxide Reactions

Hydrogen peroxide reacts chemically in a few different ways:

  1. Decomposition: As we’ve already seen, hydrogen peroxide is thermodynamically unstable. Under higher temperatures and concentrations, it decomposes to form water and oxygen. Decomposition of hydrogen peroxide can be catalysed by other compounds, such as transition metals like silver and platinum.
  2. Redox reactions: Depending on the pH level, hydrogen peroxide has powerful reducing and oxidising (redox) properties. As an oxidising agent, it can remove electrons from other substances. As a reducing agent, it can reduce various inorganic ions.
  3. Forerunner to other peroxide compounds: As a weak acid, hydrogen peroxide forms hydroperoxide when combined with various metals and their compounds.

How Is Hydrogen Peroxide Made?


As we’ve already seen, it wasn’t until the twentieth century that producing hydrogen peroxide on an industrial scale was really efficient. While the first hydrogen peroxide plant was opened in Berlin in 1873, it couldn’t produce anywhere near the quantities that are produced today.

The anthraquinone process of producing hydrogen peroxide was developed in the 1930s, patented in 1939, and is still used today.

Producing Hydrogen Peroxide Through the Anthraquinone Process

A Complete Guide to Hydrogen Peroxide - in 2015, 4.3 million tonnes of hydrogen peroxide were produced globally

This process starts with the reduction of anthraquinone to the corresponding anthrahydroquinone. In the presence of oxygen, the anthrahydroquinone oxidises – this is normally done by bubbling compressed air through an anthrahydroquinone solution. Unstable hydrogen atoms transfer to the oxygen molecule and produce hydrogen peroxide. This solution is then concentrated and purified.

While this sounds complicated, the equation for this process is fairly simple:

H2 + O2 → H2O2

This method of producing hydrogen peroxide became mainstream after the 1930s. Increased demand resulted in big leaps in production: 35,000 tonnes by 1950; over 100,000 tonnes by 1960; 300,000 tonnes by 1970. In 2015, the figure stood at 4.3 million tonnes globally.

Uses of Hydrogen Peroxide


Hydrogen peroxide is a widely used industrially, commercially, and domestically in its different concentrations.

Bleaching

Paper and pulp bleaching is what around 60% of the millions of tonnes of hydrogen peroxide produced annually is used for. It lightens and whitens paper and pulp, is odourless so doesn’t have the pungent smell of chlorine-based bleaches, and is better for the environment for the same reason.

Detergent

A Complete Guide to Hydrogen Peroxide - hydrogen peroxide is used in laundry detergents

After bleaching, hydrogen peroxide’s second main use is in the manufacture of sodium percarbonate and sodium perborate. Both of these substances are the mild bleaches found in laundry detergents. Bleach activators are often added to increase the effectiveness of the product at lower temperatures – by themselves, sodium percarbonate and sodium perborate are most effective above 60°C.

Disinfectant

Hydrogen peroxide is used as a disinfectant both commercially and domestically as it is an effective killer of viruses and bacteria. It can be used to sterilise medical equipment, and in vapour form it can sterilise whole rooms.

Cosmetics

A Complete Guide to Hydrogen Peroxide - hydrogen peroxide is used to bleach hair

Diluted hydrogen peroxide is a key ingredient in tooth whitening products and hair bleach, and of course it’s how the term ‘peroxide blonde’ came about. It can also be used to treat acne and make toothpaste, although we do not recommend DIY chemicals – hydrogen peroxide can be very harmful.

Medicine

Hydrogen peroxide is a mild antiseptic and can be used in very diluted form to clean minor cuts and scrapes. It was once used to treat major wounds but has since been found to slow healing time. It can also be used in mouthwashes.

Rocket Propellant

Yes, it’s true. Hydrogen peroxide can be used both as a mouthwash…and rocket fuel. Clearly it can only be used as rocket fuel in extremely high concentrations, and in this case it is called high-test peroxide or HTP.

Other Uses of Hydrogen Peroxide

  • Glow sticks: hydrogen peroxide reacts with di-esters and creates chemiluminescence – the glow we see in glow sticks
  • Horticulture: a weak solution of hydrogen peroxide can be used to water plants. The solution quickly decomposes and releases oxygen, which stimulates a plant’s root development
  • Stain remover: hydrogen peroxide can remove wine, chocolate, grass, mould, and armpit stains
  • Fish aeration: as for plants, a weak hydrogen peroxide solution can be used in aquariums to provide oxygen to fish

Benefits of Hydrogen Peroxide


The benefits of hydrogen peroxide are closely linked to its uses, and include:

  • Antiseptic
  • Disinfecting
  • Sanitising
  • Oxidising
  • Lightning and whitening
  • Healing (in small, weak doses)

Hazards Of Hydrogen Peroxide


As concentrations of hydrogen peroxide vary from around 3% to 90% plus, so the hazards hydrogen peroxide poses also vary.

Low concentration solutions are available over-the-counter, commonly found in brown bottles which block out the light that decomposes the hydrogen peroxide. While some people advocate ingestion, we strongly advise against it. Even a weak solution of hydrogen peroxide can cause harm when ingested, causing irritation to mucous membranes as it decomposes in the stomach. Likewise, coming into contact with hydrogen peroxide even at low concentration can also cause skin and eye irritations.

In its more highly concentrated form that’s used industrially, hydrogen peroxide is considered a hazardous chemical. As we’ve seen, it is a strong oxidiser, is corrosive, can react aggressively in the presence of a reducing agent, and can even explode on contact with organic compounds.

Safe Storage of Hydrogen Peroxide

Hydrogen peroxide should be stored in a cool (between 5-25°C), dry area away from heat and direct sunlight, and kept well away from anything flammable as it can increase the risk or intensity of fire even though it doesn’t burn itself. It should be stored in a stable container made of plastic or glass (metal containers should not be used as hydrogen peroxide can react with metals).

Hydrogen Peroxide Specification


DescriptionLimitsUnits
Hydrogen Peroxide 6% (20 Vols) – Assay19.7 – 20.3Vols
Hydrogen Peroxide 6% (20 Vols) – Assay5.7 – 6.3% w/v
Hydrogen Peroxide 30% (100 Vols) (General Use) – Assay26.5 – 28.5%
Hydrogen Peroxide 30% (100 Vols) – Assay26.5 – 28.5%
Hydrogen Peroxide 35% – Assay34.8 – 35.6% w/w
Hydrogen Peroxide 35% – AppearanceClear & colourless, free from particles

Hydrogen Peroxide Material Safety Data Sheet (MSDS)


You can find the material safety data sheets for various concentrations of hydrogen peroxide below. These MSDSs list the potential hazards (including health, fire, reactivity and environmental hazards) of hydrogen peroxide and how to use or work with it safely.

Where To Buy Hydrogen Peroxide


As we’ve previously mentioned, low concentrations of hydrogen peroxide are available to buy over-the-counter from pharmacies and supermarkets for consumer domestic use.

At ReAgent, we sell hydrogen peroxide for laboratory and industrial use at 6%, 30%, and 35% concentrations. We do not sell to consumers.

Higher concentrations of between 70% to 98% are also available but are extremely hazardous, requiring special care and dedicated storage areas.

Disclaimer

The content on chemicals.co.uk and everything published on it is provided as an information resource only. The content, its authors and affiliates accept no responsibility for any accident, injury or damage caused in part or directly from following the information provided on this website. We do not recommend using any chemical without first consulting the Material Safety Data Sheet which can be obtained from the manufacturer and following the safety advice and precautions on the product label. If you are in any doubt about health and safety issues please consult the Health & Safety Executive (HSE).

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