Hydroxide, potassium

Sodium hydroxide reacts with trichloroethylene, forming explosive mixtures of dichloroacetylene. When heated with phosphorus pentoxide, a violent explosion can result (Mellor 1946, Suppl. 1971). Phosphorus boiled with caustic soda solution can produce phosphine, which ignites spontaneously in air. Amphoteric metals such as aluminum, zinc, and tin react with sodium hydroxide, generating hydrogen, which may form explosive mixtures in air. 

Sodium hydroxide is stored in a dry place, separated from acids, metals, and organic peroxides, and protected against moisture. It is shipped in bottles, cans, and drums. 

Mild steel may be suitable as a material of construction for handling caustic soda at ambient temperature. At elevated temperatures, 60°C (140°F), corrosion may occur. Nickel and/or its alloys are most suitable for caustic handling at all temperatures and concentrations, including anhydrous molten caustic up to 480°C (896°F) (Leddy et al. 1978). Polypropylene, fluorocarbon plastics, and flberglass/vinyl ester resins are being used for many applications. Aluminum, tin, zinc, and other amphoteric metals should not be used in construction materials. 

Sodium hydroxide solutions are tested for their total alkalinity by titration with standard acid. Alkaline dusts in air may be estimated by flowing air through a 1-mm poly(tetrafluoroethylene) membrane filter, extracting the hydroxides with 0.01 N HCl under nitrogen, followed by acid-base titration using a pH electrode (NIOSH 1984, Method 7401). This method also measures the total alkaline dusts in air that includes caustic potash. 

Formula KOH MW56.il CAS [1310-58-3] Synonyms caustic potash potassium hydrate potassa 

Potassium hydroxide is produced by the electrolysis of potassium chloride solutions. 

Potassium hydroxide is used for the production of potassium carbonate, tetrapotassium pyrophosphate and other potassium phosphates, liquid fertilizers, and soaps. 

Potassium hydroxide (poe-TAS-ee-yum hy-DROK-side) is a white deliquescent solid that is available in sticks, lumps, flakes, or pellets. A deliquescent material is one that tends to absorb so much moisture from the atmosphere that it becomes very wet, even to the point of dissolving in the water it has absorbed. Potassium hydroxide also absorbs carbon dioxide from the air, changing in the process to potassium carbonate (K2C03). Potassium hydroxide is one of the most caustic materials known. It has a number of uses in industry and agriculture. 

Potassium hydroxide is chemically very active. It reacts violently with acids, generating significant amounts of heat in the process. In moist air, it corrodes metals such as tin, lead, zinc, and aluminum with the release of combustible and explosive hydrogen gas. 

Potassium hydroxide is made by the electrolysis of an aqueous solution of potassium chloride (KC1). In that process, 

Potassium hydroxide. Red atom is oxygen white atom is hydrogen and turquoise atom is potassium, publishers 

An estimate 440,000 metric tons (485,000 short tons) of potassium hydroxide were used in the United States in 2005. About 53 percent of that amount was used in the production of other potassium compounds, especially potassium carbonate (28 percent), potassium acetate, potassium cyanide, potassium permanganate, and potassium citrate. About 10 percent of all caustic potash was used in the manufacture of potassium soaps and detergents. Most soaps and detergents are made of sodium hydroxide. But potassium hydroxide can be substituted for sodium hydroxide to obtain soaps and detergents with special properties. Liquid soaps and soaps that will lather in salt water or water with a high mineral content are examples of such specialized potassium soaps. 

BP Potassium hydroxide JP Potassium hydroxide PhEur Kalii hydroxidum USPNF Potassium hydroxide 

Caustic potash E525 kalium hydroxydatum potash lye potassium hydrate. 

Potassium hydroxide is widely used in pharmaceutical formulations to adjust the pH of solutions. It can also be used to react with weak acids to form salts. 

Therapeutically, potassium hydroxide is used in various dermatological applications. 

Potassium hydroxide occurs as a white or nearly white fused mass. It is available in small pellets, flakes, sticks and other shapes or forms. It is hard and brittle and shows a crystalline fracture. Potassium hydroxide is hygroscopic and deliquescent on exposure to air, it rapidly absorbs carbon dioxide and water with the formation of potassium carbonate. 

Properties. Pure, solid potassium hydroxide [1310-58-3, KOH, caustic potash, M, 56.11, Q 2.044 g/cm mp 410 °C, bp 1327 °C, heat of fusion 7.5 kj/mol, is a hard, white substance. It is deliquescent and absorbs water vapor and carbon dioxide from the air. Potassium hydroxide dissolves readily in alcohols and water (heat of solution 53.51 kJ/mol). The solubility of KOH (g KOH/100 g H2O) in water is shown below  

The mono-, di-, and tetrahydrates are formed with water. Aqueous potassium hydroxide is a colorless, strongly basic, soapy, caustic liquid, whose density depends on the concentration  

Production. Today, potassium hydroxide is manufactured almost exclusively by potassium chloride electrolysis. The diaphragm, mercury, and membrane processes are all suitable for the production of potassium hydroxide, but the mercury process is preferred because it yields a chemically pure 50 % potassium hydroxide solution. 

In the diaphragm process, a KCl-containing, 8 -10 % potassium hydroxide solution is initially formed, whose salt content can be reduced to ca. 1.0 -1.5 % KCI by evaporation to a 50% liquor. Further purification is complicated, and the quality of liquor from mercury cells cannot be achieved. 

Since about 1985, new cell rooms for the manufacture of potassium hydroxide solution have used the membrane process. At present, the cell liquor has a low chloride content (10-50 ppm) the KOH concentration is 32%. Before dispatch, it is concentrated to 45 - 50 % by evaporation. 

By far the most important potassium compounds are the fertilizer salts (see Section 2.3). Only 5 to 6% of all potassium compounds consumed, as K2O, are utilized outside the fertilizer industry. In the Earth s crust potassium is the seventh most common element, almost as abundant as sodium. The most important potassium compounds are potassium hydroxide and potassium carbonate (potash). 

K phosphates, KBrO, kcio,. KCN, KHCO, etc. 

The manufacture of elemental potassium is unimportant with a worldwide production in the early 1990 s of less than 500 t/a. It is manufactured by the reaction of molten potassium chloride with sodium at high temperatures, whereupon a potassium/sodium alloy is formed, which is fractionally distilled. Metallic potassium is obtained in a purity of 99.5%. The formerly operated melt electrolysis of potassium hydroxide or potassium chloride is no longer operated. Potassium is utilized for the manufacture of potassium peroxide K2O2 and Na/K-alloys (reducing agent, heat carrier e.g. in the nuclear industry). 

Metallic pota.s.sium has only minor industrial importance 

19% other potassium chemicals 11% K-phosphates (K4P2O7 for liquid detergents) 

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The parent acid is unstable and always reverts to the lactone form shown. It is reconverted to acetoacetic ester by boiling alcoholic potassium hydroxide. Reduced by hydrogen iodide to dimethylpyrone. 

Crude oils contain carboxylic acids. These are analyzed by titration with potassium hydroxide and the result of the analysis is expressed in mg of KOH/g crude. 

The hydroxides M (OH)2 are generally less soluble and are of lower base strength. The Group I hydroxides are almost unique in possessing good solubility—most metal hydroxides are insoluble or sparingly soluble hence sodium hydroxide and, to a lesser extent potassium hydroxide, are widely used as sources of the hydroxide ion OH" both in the laboratory and on a large scale. 

Aluminium oxide is a white solid, insoluble in water, with a very high melting point. If heated above red heat, it becomes insoluble in acids and alkalis, and can only be brought into solution by first fusing it with sodium or potassium hydroxide when an aluminate is formed. 

This reaction has been carefully studied with the aim of obtaining the enthalpy of combustion as electrical energy, and successful hydrazine-air fuel cells have been developed using potassium hydroxide as the electrolyte. The hydrazine fuel, however, has the disadvantage that it is expensive and poisonous. 

The reaction of potassium hydroxide solution with phosphonium iodide also gives pure phosphine ... 

When chlorine is passed over molten sodium or potassium hydroxide, oxygen is evolved, the high temperature causing the chlorate V) ion to decompose ... 

B) FROM i,2-DIBROI IOETH. NE. Required Powdered potassium hydroxide, 25 g. rectified spirit, 100 ml. ethylene dibromide, 15 ml. (33 g.). 

Alcoholic potassium hydroxide gives an unsaturated hydrocarbon, often however in only low yield with the earlier members of the series. 

Required Acetone, 60 ml. 30% aqueous potassium hydroxide, 90 ml. sodium, 17 g. 

If only 100 ml. separating-funnels are available, the distillate must be divided into two portions and each extracted with ether as described, the final ether extracts being united for drying with potassium hydroxide. 

The benzene used in this preparation should be reasonably free from toluene therefore use a sample of benzene supplied by dealers as crystalUsable benzene, i.e.y one which crystallises readily when cooled in ice-water. It should preferably be dried over calcium chloride and, immediately before use, filtered through a fluted filter-paper. The pyridine should also preferably be dried over solid potassium hydroxide and redistilled. 

When an aqueous solution of benzenediazonium chloride is added to a cold concentrated solution of potassium hydroxide, the unstable potassium diazo-tate, C(HjN NOK, is formed, and this when heated with alkali to 130° changes to the isomeric but far more stable potassium isodiazotate it is probable that these copipounds have the structures (A) and (B) respectively. 

Required Cyclohexanone, 20 g. hydroxylamine hydrochloride, 17 g. anhydrous sodium carbonate, 13 g. concentrated sulphuric acid, 50 ml. 25% aqueous potassium hydroxide solution, approx. 200 ml. chloroform, 120 ml. 

The cost of this preparation (particularly for large classes) can be appreciably reduced by using a solution of 20 g. of sodium hydroxide in 25 ml. of water, in place of the potassium hydroxide solution. In this case, however, the product on standing overnight forms a very hard mass, which should be dissolved in tcarm water. The yields of alcohol and acid are unchanged. 

When benzii is heated with potassium hydroxide solution, it undergoes a molecular rearrangement with the formation of the potassium salt of benzilic acid, or diphenyl lycollic acid ... 

Dissolve 5 g. of benzii in 15 ml. of boiling ethanol in a conical flask fitted with a reflux water-condenser. Then add a solution of 5 g. of potassium hydroxide in 10 ml. of water, and heat the mixture (which rapidly develops a purple colour) on a boiling water-bath for about 15 minutes. Cool and stir the solution, from which the potassium benzii ate separates in fine cr> stals. 

Transfer the quinoline chlorozincate to a beaker, add a small quantity of water, and then add 10% sodium hydroxide solution until the initial precipitate of zinc hydroxide completely redissolves, and the free quinoline separates. Transfer the mixture to a separating-funnel, wash out the beaker with ether, adding the washings also to the solution in the funnel, and then extract the quinoline twice with ether. Dry the united ethereal extracts by adding an ample quantity of powdered potassium hydroxide and... 

Since the silver salts of the carboxylic acids are usually soluble in dilute nitric acid, they must be prepared by treating an aqueous solution of a neutral salt of the acid (and not the free acid itself) with silver nitrate solution. It is not practicable to attempt to neutralise the acid with sodium or potassium hydroxide solution, because the least excess of alkali would subsequently cause the white silver salt to be contaminated with brown silver oxide. The general method used therefore to obtain a neutral solution j to dissolve the acid in a small excess of ammonia solution, and then to boil the solution until all free... 

The molecular weight of many carboxylic acids which arc freely soluble in cold water (i.e., chiefly the aliphatic acids) can readily be obtained by titrating a known weight of the acids in aqueous solution with standard sodium or potassium hydroxide solution, using phenolphthalein as an indicator. To avoid the use of unduly large quantities of the acid, it is advisable to use Mj2 caustic alkali solution, and in order to obtain a sharp end>point, this alkali solution... 

The purification train. The oxygen is led from the cylinder through Ordinary flexible rubber condenser tubing to the constant level device A (Fig. 85). This consists of two concentric tubes (approximately 2 cm. and 0-5 cm. respectively, in diameter the inner tube being narrowed and curved at the bottom as shown) immersed in 50% aqueous potassium hydroxide contained in the outer vessel (diameter 3-5 cm.). Then by adjusting the liquid level in A the pressure of oxygen may be kept constant, and at a maximum of about... 

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