Hydrogen peroxide is an inorganic compound with the chemical formula of H2O2, and its aqueous solution is a colorless and transparent liquid. We often say that hydrogen peroxide is hydrogen peroxide solution. Generally, pure hydrogen peroxide is a light blue viscous liquid, which can be mixed with water in any proportion. Suitable for medical wound disinfection, environmental disinfection and food disinfection.
Hydrogen peroxide itself is a chemical substance, and only the chemical substance obtained by mixing with water is called hydrogen peroxide. Pure hydrogen peroxide is not hydrogen peroxide.
Physical and chemical properties of hydrogen peroxide
1, physical properties
Hydrogen peroxide is a blue viscous liquid, soluble in water, alcohol and ether, insoluble in benzene and petroleum ether. The aqueous solution is a colorless and transparent liquid with a melting point of -0.43℃ and a boiling point of 150.2℃. The molecular configuration of pure hydrogen peroxide will change, so the melting boiling point will also change. The solid density at freezing point is 1.7 1g/cm_, and the density decreases with the increase of temperature.
2. Chemical properties
(1) oxidation: Hydrogen peroxide is a very strong oxidizing agent.
(2) Reducibility: it reacts with strong oxidants such as chlorine and potassium permanganate and is oxidized to generate oxygen.
(3) Hydrogen peroxide is a very weak acid, and metal peroxide can be regarded as its salt.
(4) Pure hydrogen peroxide is very unstable. When heated to153 C, it is violently decomposed into water and oxygen.
(5) When hydrogen peroxide is decomposed by heat, it reacts violently with chromic acid, potassium permanganate, metal and carbonic acid, releasing oxygen and water.
Third, how to make hydrogen peroxide?
The preparation methods of hydrogen peroxide are divided into industrial preparation method and laboratory preparation method, among which there are different preparation methods. Let me give you a brief introduction:
1, industrial method
Preparation method of (1) alkaline hydrogen peroxide
A quinone-containing air electrode for producing alkaline hydrogen peroxide, each pair of electrodes consists of an anode plate, a plastic net, a cation diaphragm and a quinone-containing air cathode. The upper and lower ends of the electrode working area are provided with a distribution chamber for fluid to enter and a collection chamber for fluid to discharge, and the fluid inlet is provided with a throttle hole. Multi-component electrodes are connected in series through finite dipoles, and the plastic hoses at the inlet and outlet of the anode circulating alkaline water are lengthened and then connected to the liquid collection header.
(2) phosphoric acid neutralization method
Neutralizing the sodium hydroxide solution to pH 8.0 ~ 8.7 with phosphoric acid or sodium dihydrogen phosphate to generate an aqueous solution of NaH2PO4 and H2O2, cooling the obtained aqueous solution to 5 ~-5℃, and precipitating most of nah2po4 in the form of nah2po410h2o hydrate; Then that mixture contain NaH2PO410h2o hydrate and hydrogen peroxide aqueous solution is separated in a centrifugal separator, the aqueous solution contain a small amount of nah 2 po 4 and hydrogen peroxide is evaporated in an evaporator to obtain steam containing H2O2 and H2O, and the concentrated salt solution of nah2po4 contain hydrogen peroxide flows out from the bottom and returns to a neutralization tank; Then, the steam containing H2O2 and H2O is fractionated under reduced pressure in a fractionator, and about 30% of H2O2 product can be obtained.
(3) electrolytic sulfuric acid method
Hydrogen peroxide with a concentration of 95% can be obtained by electrolyzing 60% sulfuric acid and then hydrolyzing it.
(4)2- ethyl anthraquinone method
2-ethylanthraquinone reacts with hydrogen at a certain temperature and pressure to generate 2- ethyl hydroanthraquinone, and 2- ethyl hydroanthraquinone reacts with oxygen at a certain temperature and pressure, and 2- ethyl hydroanthraquinone is reduced to generate 2-ethylanthraquinone and hydrogen peroxide at the same time. Then extracting to obtain aqueous hydrogen peroxide solution, and finally purifying with heavy aromatic hydrocarbon to obtain qualified aqueous hydrogen peroxide solution.
2. Laboratory methods
(1)100 ml15-18% sulfuric acid, gradually adding about 40g barium peroxide under ice cooling, and pouring out the upper solution to obtain a hydrogen peroxide solution. If necessary, it can be extracted with 20mL each time for 4-5 times, the ether extract is evaporated in a water bath (not higher than 40℃) to remove ether, and the residue is transferred to a sulfuric acid drying bottle. 50% hydrogen peroxide solution can be prepared by this method.
(2) Under strong stirring, 90g of sodium peroxide is added into 800ml of 20% sulfuric acid cooled by ice water, left for 65438±02h, and precipitated sodium sulfate decahydrate crystals are filtered out; The filtrate was placed in a milling vacuum device (5- 10mm) and distilled at a bath temperature of 60-65 degrees Celsius (finally at 85 degrees Celsius), with the distillation amount of100ml; Every time; Distillates are collected by two receivers in series (the second receiver uses ice cooling). The product in the first receiver contains more than 20% hydrogen peroxide, and the product in the second receiver contains less than 3% hydrogen peroxide. The obtained hydrogen peroxide solution can be further concentrated in a concentrated sulfuric acid vacuum dryer at room temperature, and the 25% solution can be concentrated to 88% after three days.