Hydrogen peroxide

Hydrogen peroxide is a chemical compound with the formula H2O2.

The simplest peroxide, a compound with an oxygen–oxygen single bond.

It is used as an oxidizer, bleaching agent and antiseptic.

Concentrated hydrogen peroxide is a reactive oxygen species and has been used as a propellant in rocketry.

Has an unstable peroxide and slowly decomposes in the presence of light.

It is typically stored with a stabilizer in a weakly acidic solution, because of its instability.

Enzymes that use or decompose hydrogen peroxide are classified as peroxidases.

It is most commonly available as a solution in water, and is usually available from pharmacies at 3 and 6 wt% concentrations.

It’s rate of decomposition increases with rising temperature, concentration and pH, with cool, dilute, acidic solutions showing the best stability.

Decomposition is catalysed by various compounds, including most transition metals and their compounds.

The decomposition of hydrogen peroxide liberates oxygen and heat, and spilling high-concentration hydrogen peroxide on a flammable substance can cause an immediate fire.

In acidic solutions, it is one of the most powerful oxidizers known, and can be used for removing organic stains from laboratory glassware.

Hydrogen peroxide is a weak acid, forming hydroperoxide or peroxide salts with many metals.

It is both an oxidizing agent and reducing agent.

Hydrogen peroxide is formed ias a short-lived product in biochemical processes and is toxic to cells.

SOD (superoxide dismutase), biological enzymes arebimportant antioxidant agents.

Superoxide dismutases promote the disproportionation of superoxide into oxygen and hydrogen peroxide, which is then rapidly decomposed by the enzyme catalase to oxygen and water.

Hydrogen peroxide can also form from the degradation of adenosine monophosphate which yields hypoxanthine.

Hypoxanthine is then oxidatively catabolized first to xanthine and then to uric acid, and the reaction is catalyzed by the enzyme xanthine oxidase.

Degradation of hypoxanthine through xanthine to uric acid to form hydrogen peroxide.

Hydrogen peroxide is a molecule of plant defense against pathogens.

Hydrogen peroxide is a major factor implicated in the free-radical theory of aging.

About 60% of the world’s production of hydrogen peroxide is used for pulp- and paper-bleaching.

It is used in polymerisations, as a flour bleaching agent and as a treatment for acne.

It is used in certain waste-water treatment processes to remove organic impurities.

Hydrogen peroxide can be used for the sterilization of various surfaces including: surgical tools and may be deployed as a vapour (VHP) for room sterilization.

It demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores, and has greater activity is seen against Gram-positive than Gram-negative bacteria.

The presence of catalase or other peroxidases in these organisms can increase tolerance, and higher concentrations of H2O2 and longer contact times are required for sporicidal activity.

Hydrogen peroxide is seen as an environmentally safe alternative to chlorine-based bleaches, as it degrades to form oxygen and water.

Historically hydrogen peroxide was used for disinfecting wounds, partly because of its low cost and prompt availability compared to other antiseptics.

Now recognized to inhibit healing and to induce scarring because it destroys newly formed skin cells.

A very low concentration of H2O2 can induce healing, and only if not repeatedly applied.

Dermal exposure to hydrogen peroxide causes whitening or bleaching of the skin due to microembolism caused by oxygen bubbles in the capillaries.

Diluted H2O 2 (between 1.9% and 12%) mixed with ammonium hydroxide is used to bleach human hair.

It is also used for tooth whitening, and is found in most whitening toothpastes.

Hydrogen peroxide works by oxidizing colored pigments onto the enamel

When mixed with baking soda and salt it makes a home-made toothpaste.

May be used to treat acne.

The ingestion or injection of hydrogen peroxide is therefore believed to kill disease by mimicking the immune response in addition to increasing levels of oxygen within the body.

Its effectiveness and safety is scientifically questionable.

It is produced by the immune system in a carefully controlled manner, and phagocytes engulf pathogens and then use hydrogen peroxide to destroy them.

The peroxide is toxic to both the cell and the pathogen and is kept within a phagosome.

Free hydrogen peroxide will damage any tissue it encounters via oxidative stress.

Large doses of orally administered hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea.

Intravenous injection of hydrogen peroxide can lead to death.

Hydrogen peroxide domestic uses include cleaning and disinfecting agents.

Hydrogen peroxide reacts with certain di-esters, to produce chemiluminescence, commonly encountered in the form of glow sticks.

Some horticulturists advocate the use of weak hydrogen peroxide solution in watering solutions, as spontaneous decomposition releases oxygen that enhances a plant’s root development and helps to treat root rot.

Low concentrations, such as 6%, are widely available and legal to buy for medical use.

Most over-the-counter peroxide solutions are not suitable for ingestion.

Higher concentrations may be considered hazardous.

In high concentrations it is an aggressive oxidizer and will corrode human skin.

In the presence of a reducing agent, high concentrations of H2O2 will react violently.

It should be stored in a cool, dry, well-ventilated area and away from any flammable or combustible substances.

It should be stored in a container composed of non-reactive materials such as stainless steel or glass, some plastics and aluminium alloys may also be suitable.

Because it breaks down quickly when exposed to light, it should be stored in an opaque container.

It forms explosive mixtures upon contact with organic compounds.

Highly concentrated hydrogen peroxide itself is unstable and can cause a boiling liquid expanding vapour explosion, and it also corrosive and can cause irritation to the eyes, mucous membranes and skin.

Swallowing hydrogen peroxide leads to decomposition in the stomach and releases large quantities of gas leading to internal bloating.

Inhaling it over 10% can cause severe pulmonary irritation.

Hydrogen-peroxide vapour is potentially hazardous.

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