What is H2O2??

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Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in a dilute solution, slightly more viscous than water. It has strong oxidizing properties and is therefore a powerful bleaching agent that has found use as a disinfectant, as an oxidizer, and in rocketry (particularly in high concentrations as high-test peroxide (HTP) as a monopropellant), and in bipropellant systems.

History
Hydrogen peroxide was first isolated in 1818 by Louis Jacques Thénard by reacting barium peroxide with nitric acid. An improved version of this process used hydrochloric acid, followed by sulfuric acid to precipitate the barium chloride byproduct. Thenard's process was used from the end of the 19th century until the middle of the 20th century. Modern manufacture methods are discussed below.

Uses

Industrial applications
About 50% of the world's production of hydrogen peroxide in 1994 was used for pulp- and paper-bleaching. Other bleaching applications are becoming more important as hydrogen peroxide is seen as an environmentally-benign alternative to chlorine-based bleaches.

Other major industrial applications for hydrogen peroxide include the manufacture of sodium percarbonate and sodium perborate, used as mild bleaches in laundry detergents. It is used in the production of certain organic peroxides such as dibenzoyl peroxide, used in polymerisations and other chemical processes. Hydrogen peroxide is also used in the production of epoxides such as propylene oxide. Reaction with carboxylic acids produces a corresponding "per-acid". Peracetic acid and meta-chloroperoxybenzoic acid (commonly abbreviated mCPBA) are prepared from acetic acid and meta-chlorobenzoic acid, respectively. The latter is commonly reacted with alkenes to give the corresponding epoxide.

2006-12-22 09:51:52 補充：
Domestic usesDiluted H2O2 (around 5%) is used to bleach human hair, hence the phrases peroxide blonde and bottle blonde. It can absorb into skin upon contact and create a local skin capillary embolism which appears as a temporary whitening of the skin.

2006-12-22 09:52:34 補充：
It whitens skeletons that are to be put on display. 3% H2O2 is used medically for cleaning wounds, removing dead tissue, or as an oral debriding agent. Most over-the-counter peroxide solutions are not, however, suitable for ingestion.

2006-12-22 09:53:15 補充：
The Food and Drug Administration (FDA) has classified hydrogen peroxide as a Low Regulatory Priority (LRP) drug for use in controlling fungus on fish and fish eggs. See ectoparasite.

2006-12-22 09:54:09 補充：
Some gardeners and hydroponics implementers have professed the value of hydrogen peroxide in their watering solutions. They claim its spontaneous decomposition releases oxygen to the plant that can enhance root development and also help treat root rot,

2006-12-22 09:54:42 補充：
which is cellular root death due to lack of oxygen.Laboratory tests conducted by fish culturists in recent years have demonstrated that common household hydrogen-peroxide can be used safely to provide oxygen for small fish.

2006-12-22 09:55:32 補充：
Citation Reference Hydrogen-peroxide releases oxygen by decomposition when it is exposed to catalysts.Hydrogen peroxide is increasingly popular for the treatment of hydrogen sulfide and iron. Catalytic carbon and redox media perform well with hydrogen peroxide pretreatment.

2006-12-22 09:56:58 補充：
Generally 90% of the reaction between hydrogen peroxide and hydrogen sulfide takes place within 10 to 15 minutes, with the balance reacting in an additional 20 to 30 minutes. The sulfur in hydrogen sulfide H2S) is in the -2 state.

過氧化氫，俗稱雙氧水。化學性質不穩定，一般以30%或60%的水溶液形式存放。分子式H2O2
性質
純過氧化氫是淡藍色的粘稠液體，熔點-0.7℃，沸點150℃。凝固點時固體密度為1.71g·cm-3，密度隨溫度升高而減小。H2O2的締合程度比H2O大，所以它的介電常數和沸點比水高。純H2O2比較穩定，若加熱到153℃便猛烈的分解為水和氧氣。


H2O2可溶於乙醇、乙醚，不溶於苯。對有機物有很強的氧化作用，一般作為氧化劑使用。

重金屬離子Fe2+、Mn2+、Cu2+等對H2O2的分解有催化作用；H2O2在酸性和中性介質中較穩定，在鹼性介質中易分解；用波長為320～380nm的光照射會使H2O2分解速度加快，故H2O2應盛於棕色瓶中並放在陰涼處。

過氧化氫主要用於紙漿、天然纖維及牙齒等的漂白，也是染髮劑的成份之一，還用作合成有機原料（鄰苯二酚）的材料，醫藥、金屬表面處理劑，聚合引發劑等。還可用作火箭推進劑