Hydrogen Peroxide
Hydrogen peroxide is a colorless liquid that has a bitter taste and is caustic to skin. Pure H2O2 is a thick liquid like syrup that it quickly decomposes into oxygen and water. Usually it is sold in weaker solutions (most commonly 3 percent), diluted with water.
In nature, hydrogen peroxide occurs only in trace amounts, mostly in snow and rain. It is produced in the atmosphere during lightening storms. Additionally, it can be manufactured easily using electrochemical processes. However, concentrated hydrogen peroxide can start fires if dripped onto wood or paper, so it must be carefully handled and stored.
One of the first things that Louis Thenard found out about hydrogen peroxide was that it attacks the skin, producing painful blotches. Fortunately, this effect wore off completely within a few hours. Thenard had tried for many months to formulate the chemical, now known to be H2O2; at the time, scientists did not know how much oxygen could be combined with water. In late 1818, he finally succeeded in preparing pure hydrogen peroxide, which he called "oxygenated water," and determined its density.
Besides attacking the skin, the chemical also reacted explosively with metal oxides, as Thenard soon discovered. For several years afterward, he continued to study the compound, defining its properties and using it to prepare new peroxides (other compounds containing extra oxygen). When he published his work on hydrogen peroxide, a colleague suggested that the chemical might be used to restore old paintings by removing sulfur compounds from their surface.
Today, hydrogen peroxide has found many more valuable applications, mainly in industry, but also for household and cosmetic purposes. Because the chemical is a strong oxidant (it combines with other compounds to produce oxides and water), it is widely used as a commercial bleaching agent in the production of cotton, wool, and other textile fibers, and in the pulp and paper industry. Even though it costs more than chlorine bleach, hydrogen peroxide is preferred in these applications because its action on fibers is milder and it leaves no undesirable residues. The chemical is also used cosmetically in hair bleach. More than half of the hydrogen peroxide produced in the United States is consumed in various bleaching processes.
The chemical is also used to make organic solvents, plasticizers, stabilizers, and other products. Because of hydrogen peroxide's germ-killing properties, which were explored by French bacteriologist Charles-Edouard Chamberland (1851-1908) in the late 1800s, many people use it as a topical antiseptic and mouthwash.
During the 1940s, American biophysicist Britton Chance (1913-) used hydrogen peroxide to study enzyme activity; his results paved the way for scientists to determine the connection between enzymes and nucleic acids. In its concentrated form, hydrogen peroxide has also found high-technology applications in steering spaceships and as a fuel additive for rockets, submarines, and jet planes.
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