H2O2--a molecule of two hydrogen atoms and two oxygen atoms. It decays into water (H2O) and oxygen (O2) when exposed to energy in the form of heat or light. It is a powerful oxidizing agent, and is sold diluted with water. It is used in low concentrations as a disinfectant (Halcyon--I was waiting for someone to point out that out. I don't use hydrogen peroxide myself. I find it amusing that various websites recommend bathing in it to "restore," "rejuvenate," and "refresh" the body), to "bleach" hair, and in higher concentrations for various industrial and environmental uses.

Its one of those many household chemicals that everyone should have vast quantities of in their cabinet for divers and sundry purposes.

Hydrogen peroxide is a good disinfectant because it is quite toxic to cells. Sure, it decomposes into water and oxygen, both of which aren't toxic in their own right, but the important thing is that an intermediate hydroxyl radical is formed. Free radicals, as you are most likely aware, can cause a lot of damage to cells. They can cut or cause mutations in DNA and disrupt cellular processes.

generation of free radicals:

H2O2 -> .OH + .OH

Free radicals will kill your cells just as easily as they will kill bacteria. The hope is that you have a lot more cells than bacteria and the damage to you will be minimal.

Free radicals are also generated during regular cellular processes such as respiration. As a result, nature has evolved peroxidases which can neutralize free radicals before they cause cell damage. The one that interacts with hydrogen peroxide is catalase. The reason hydrogen peroxide fizzes more vigorously on a cut than it does in the bottle is the catalase reacts with the peroxide and releases oxygen. You can observe the same phenomenon by pouring hydrogen peroxide on a piece of meat, especially liver.

Hydrogen Peroxide can also be used as a fuel, when used in high concentrations. The first use of high strength Hydrogen Peroxide, known as HTP, (High Test Peroxide) was in the Heinkel He 52 aircraft, which was first flown in 1937.

Today, the Russian Navy use Hydrogen peroxide to power their torpedoes. Britain's Royal Navy does not, as they consider it too dangerous. They lost an S class submarine (the HMS Sidon) in 1955 due to a 'hydrogen peroxide torpedo explosion'. A similar accident is the popular theory for what caused the damage to the Russian submarine, the Kursk.

Hydrogen Peroxide was used to fuel the British Black Arrow rocket; used to put Britain's first (and currently, only) satellite in orbit in 1971.


The history of torpedoes (including hydrogen peroxide propulsion) in the United States Navy is detailed here. http://members.dialnet.net/rrupert/ustorp3.html

For far more detail than you could ever need on the use of Hydrogen Peroxide as a fuel can be found at the 1st HTP Propulsion Workshop:
http://www.ee.surrey.ac.uk/SSC/H2O2CONF/

Information about every Royal Navy submarines ever, including the HMS Sidon can be found at
http://www.argonet.co.uk/users/jdholt/

Enough of the chemical side of hydogen peroxide- let's learn about the bleaching abilities of the hairdresser's best friend!

According to the London Science Museum the chemical is present at low strength in the air, rain and, mildly concentrated, in ice. The hydrogen peroxide in the air is apparently responsible for the "brilliant finish" given to cloth hung outside on a frosty day. The powers of hydrogen peroxide were originally "discovered" by Louis Auguste Thenard in 1818.

It remained "just another chemical" to the everyday schmoe until 1867 when E.H Thiellay, a pharmacist and perfumer of London, and Leon Hugo, a Parisian hairdresser, banded together. They created "Eau de Fontaine de Jouvence Golden" (which Babelfish translates as "Water of Fountain of Youth Golden Delicious"), a 3% solution of the chemical. And hair bleach was born and became popular...

... at the same time that hydrogen peroxide was experimented with for use in military matters: The chemical was used in submarines and as a fuel for torpedoes and rockets in World War II. It has also been used, and continues to be used, as a bleaching agent for textiles (such as wool and silk) and paper.

But hydrogen peroxide remains most famous for its hair-bleaching abilities. The industry is a multi-million dollar one, and over $1 billion dollars is spent on home hair colour in the US per year.

Swinburne sums up the international obsession with blondness best:

"Yea, is not even Apollo, with hair and harpstring of gold
A bitter God to follow, a beautiful God to behold?"
--Swinburne 1837- 1909

I guess Apollo must have found and used the original "Water of Fountain of Youth Golden Delicious".
The jet pack, which in the late Sixties was what we were told we'd all be using to get around ca. 2000, was powered by high strength hydrogen peroxide. Aside from the volatile (and thus dangerous) fuel, a major drawback was that the backpack sized units only carried enough fuel for thirty seconds or so of flight.

For demonstrations, such as at football games, the pilot would fuel-up in the parking lot and fly up over the stands and land on the playing field. Longer filmed sequences of guys jet packing over the countryside were painstakingly edited together from many separate flights.
Hydrogen peroxide is also useful for anyone who likes to make big, loud, colourful explosions.

Mix 30 ml of 20 volume hydrogen peroxide solution with 20 ml of ethanol. Light the mixture, add 0.5 g of potassium permanganate and stand back. You are guaranteed fun.

These figures are given by http://www.cce.paisley.ac.uk, which also suggests you carry out the reaction in a fume cupboard and light the mixture with a taper. However having seen it carried out by a teacher this morning, I can confirm it is perfectly safe to do it in open air and get the flame going with a cigarette lighter.

What actually happens is this. Hydrogen peroxide is unstable and decomposes (even at room temperature, though slowly) to oxygen and water. Potassium permanganate is a very good catalyst for this decomposition, so the hydrogen peroxide will decompose much more quickly. In the above demonstration, this decomposition takes place underneath burning ethanol. The oxygen being released, which of course at this point is pure rather than at 20% as in air, is thus exposed to the ethanol. Oxygen is naturally a good way to encourage fire (considering that combustion is oxidation), so the low-level flames on the ethanol erupt into a column of explosions.

Rubbing hydrogen peroxide into an itch (such as a mosquito bite) will stop the itch almost instantly. I rubbed some hydrogen peroxide on mosquito bites on my arm and it stopped the itch on the spot. Perhaps you should a cotton ball or some tissue paper to rub the peroxide into the itch. It may foam, it may not, who's to say, but it will stop that awful itch.

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