The potassium hydroxide it is a white crystalline inorganic solid. Its chemical formula is KOH. Its crystals easily absorb water from the air, which is why it is said to be a hygroscopic compound. It is a strong base and absorbs carbon dioxide (COtwo) of the environment.
Industrially it is produced by electrolysis of potassium chloride (KCl). For energy conservation reasons and for the purity of the product, mercury (Hg) cells are used in this method..
But for many years there has been concern about mercury contamination generated by this process. In fact, discharge into the environment of waste effluents containing mercury is strictly prohibited. There are other processes such as diaphragm and membrane, but mercury is preferred because it produces a 50% pure KOH solution..
There are also non-electrochemical processes such as the decomposition of potassium nitrite (KNOtwo) in the presence of ferric oxide (FetwoOR3).
KOH solutions obtained in industrial processes are evaporated to achieve 90-95% KOH. The residual content of 5-10% water is bound to KOH in the form of potassium hydroxide monohydrate (KOH.HtwoOR).
Due to its caustic properties and its strong basicity, it has a wide variety of applications. It serves as a raw material in soaps and detergents, printing inks or cosmetics, among other uses. It is also used to wash industrial gases, in the detection of fungi by microscope and has application in the food industry.
Although it is a very stable compound, it is classified as corrosive. It must be handled with care, as it can cause burns to eyes, skin and mucous membranes.
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The KOH crystal at ordinary temperatures is monoclinic, with each potassium (K) atom surrounded by a distorted octahedron of oxygen (O) atoms. In turn, the hydroxyl groups (OH) form a chain in the form of a zig-zag linked by hydrogens, where the O-O distances are 3.35 A, ruling out any significant hydrogen bonding..
At high temperatures, KOH has a cubic crystalline form.
- Potassium hydroxide.
- Caustic potash.
- Potassium hydrate.
- Potassium bleach.
White crystalline solid.
56.106 g / mol.
380 ° C; 406 ºC has also been reported (varies according to water content). Technical grade (90-92% KOH) melts at approximately 250 ° C.
1327 ºC.
2.044 g / cm3
Soluble in cold water (107 g / 100 ml at 15 ºC) and in hot water (178 g / 100 ml at 100 ºC). Its dissolution in water is a very exothermic process, this means that a large amount of heat is generated.
Soluble in alcohols. Soluble in glycerin. Insoluble in ether.
13.5 (in 0.1 molar aqueous solution).
Its crystals are deliquescent or hygroscopic, which means that it absorbs water from the air. It also easily absorbs COtwo from air.
Its chemical reactions are the characteristics of a strong base. In aqueous solution it reacts with any weak acid to form the potassium salt of the acid. For example, it reacts with carbonic acid (HtwoCO3) or with carbon dioxide (COtwo) to form bicarbonate or potassium carbonate.
Reacts with alcohols to form potassium alkoxides, or with hydrogen sulfide HtwoS to form potassium sulphide or bisulphide.
In aqueous systems KOH forms various hydrates: mono-, di- and tetrahydrates.
Aqueous KOH solutions are colorless, strongly basic, soapy, and caustic. It is a corrosive material, both solid and in solution.
It is not flammable, but when heated to decomposition it emits toxic and corrosive K fumestwoOR.
It causes severe burns to eyes, skin and mucous membranes and in contact with metals, such as aluminum, tin, lead or zinc, it can generate the evolution of hydrogen gas (Htwo), which is highly flammable.
The heat produced by coming into contact with moisture or other substances can create enough heat to ignite combustible materials..
Potassium hydroxide is used as a raw material for the chemical and pharmaceutical industry. It is used to produce potassium carbonate (KtwoCO3), potassium permanganate (KMnO4), potassium phosphate (K3PO4), potassium silicate (KtwoYes3) and potassium cyanide (KCN), among other compounds.
High purity KOH has application in the manufacture of pesticides, synthesis of inks and dyes, chemicals for gums, in photography as an alkali photo developer, as an electrolyte in alkaline batteries and fuel cells, in the electrolysis of water, in electrodeposition. or electroplating, lithography, etc.
Technical grade KOH is used as a raw material in the detergent and soap industry; in the manufacture of cosmetics, glass and textiles; to desulfurize crude oil; as a drying agent and in paint and varnish removers, among other applications.
It is also useful as a caustic agent in the wood industry, in cotton mercerization, in analytical chemistry for alkalimetric titrations, in organic synthesis and in water treatment..
In medicine, it is used in wet mounting during the preparation of clinical specimens for microscopic visualization of fungi and other fungal elements in skin, hair, nails, among others..
The KOH preparation is used to clarify clinical material so that fungal elements can be more easily seen.
A clinical sample fragment is added to a portion of 10% KOH solution on a glass slide. It is then covered with a cover-object and allowed to stand at room temperature to allow the host cells to digest. Finally, it is observed with the microscope.
On the other hand, KOH in the form of a topical solution is effective in the treatment of warts..
It is used in some cleaning products for nails, shaving creams and soaps, as its corrosive property makes it very effective in the decomposition or removal of soft tissue and hair removal.
It is used in fertilizers and other agricultural products such as herbicides and pesticides.
KOH is useful in cleaning operations and in washing or purifying industrial gases, especially when acid removal is required..
For example, due to its ease of reacting with COtwo, it is used to absorb this gas. In addition, it is ideal for reacting with acids, which is why it is used to remove hydrogen sulfide (HtwoS). And similarly, to remove nitrogen oxides.
It is used to adjust pH, as a stabilizer and as a thickening agent in the food industry.
It has been considered by the US Food and Drug Administration, or FDA. Food and Drug Administration), as a direct ingredient in human food, provided that it is used under the conditions related to good manufacturing practices.
Biodiesel is a liquid fuel substitute for diesel or diesel. It is obtained from vegetable oils or animal fats. KOH has been used as a catalyst in the production of biodiesel.
For several years, attention has been paid to the pollution of the seas by plastic waste, which affects more than 550 species of marine fauna, both by ingesting plastic and by being trapped in the waste.
For this reason, attempts are being made to find methods that allow the processing of samples from the digestive tract of animals, dissolving the organic material but without dissolving the plastics ingested by the specimens.
In this sense, it has been found that the use of KOH solutions to separate plastics from organic matter is a practical and effective method, which can be very useful in quantitative studies of plastic ingestion by wild marine fauna..
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