Word Finder - potassium

definition

A soft, waxy, silvery reactive metal that is never found unbound in nature; an element (symbol K) with an atomic number of 19 and atomic weight of 39.0983. The symbol is derived from the Latin kalium.

definition

A single atom of this element.

It is slightly soluble in potassium sulphide.

On oxidation with potassium permanganate it is converted into acetyl urea, together with other products.

The yellow precipitate obtained is washed with a solution of potassium acetate and finally with dilute alcohol.

It is insoluble in dilute acids, but is readily soluble in excess of potassium cyanide.

It was found, for instance, that a film of insoluble copper ferrocyanide, deposited in the walls of a porous vessel by the inward diffusion and meeting of solutions of copper sulphate and potassium ferrocyanide, would allow water to pass, but retained sugar dissolved in that liquid.

They are soluble in water and give characteristic precipitates with platinic and auric chlorides, and with potassium ferrocyanide.

Its methyl derivatives yield the corresponding carboxylic acids when oxidized by potassium permanganate.

In two cases, however, it has been found in the absence of appreciable quantities of uranium and thorium compounds, namely in beryl, and in sylvine (potassium chloride).

Here the other metal may be one, such as potassium, or two, such as potassium and sodium, and, in the latter case, the proportion between the two may vary continuously throughout wide limits.

It is also obtained by heating para-chlorphenoldisulphonic acid with potassium hydroxide.

By passing the vapour of this compound through a red-hot tube, it yields the isomeric a0- pyridylpyrrol, the potassium salt of which with methyl iodide gives a substance methylated both in the pyridine and pyrrol nuclei.

Suppose, for instance, the paper ribbon to be soaked in a solution of iodide of potassium and a light contact spring made to press continuously on its surface as it is pulled forward by the mechanism.

Cadmium hydroxide, Cd(OH) 2, is obtained as a white precipitate by adding potassium hydroxide to a solution of any soluble cadmium salt.

The potassium salt, after recrystallization from warm water, separates in large tabular crystals.

The solution obtained may be evaporated in vacuo until it attains a density of 1.46 when, if partially saturated with potassium hydroxide and filtered, it yields crystals of potassium pentathionate, K 2 S 5 0 6.3H 2 0.

Hexathionic acid, H 2 S 6 0 6, is probably present in the mother liquors from which potassium pentathionate is prepared.

The solution on the addition of ammoniacal silver nitrate behaves similarly to that of potassium pentathionate, but differs from it in giving an immediate precipitate of sulphur with ammonia, whereas the solution of the pentathionate only gradually becomes turbid on standing.

Thus the equation Cl 2 -1-2KI, Aq=2KC1, Aq+12+52400 cal., or (C12) +2KI, Aq =2KC1, Aq+[12]-I-52400 cal., would express that when gaseous chlorine acts on a solution of potassium iodide, with separation of solid iodine, 52400 calories are evolved.

Many esters of malonic acid have been prepared, the most important being the diethyl ester (malonic ester), CH 2 (000C 2 H 5) 2, which is obtained by dissolving monochloracetic acid in water, neutralizing the solution with potassium carbonate, and then adding potassium cyanide and warming the mixture until the reaction begins.

The half nitrile of malonic acid is cyanacetic acid, CN CH 2 COOH, which, in the form of its ester, may be obtained by the action of a solution of potassium cyanide on monochloracetic acid.

Potassium cyanide reacts with this acid to form the corresponding dinitrile, which is converted by hydrochloric acid into citric acid.

Held synthesized the acid from ethyl chlor-acetoacetate (from chlorine and acetoacetic ester) by heating with potassium cyanide and saponifying the resulting nitrile.

With fused potash it forms potassium oxalate and acetate.

The impurities occasionally present in commercial citric acid are salts of potassium and sodium, traces of iron, lead and copper derived from the vessels used for its evaporation and crystallization, and free sulphuric, tartaric and even oxalic acid.

Tartaric acid, which is sometimes present in large quantities as an adulterant in commercial citric acid, may be detected in the presence of the latter, by the production of a precipitate of acid potassium tartrate when potassium acetate is added to a cold solution.

Potash soap with the same reagent undergoes double decomposition - a proportion being changed into a soda soap with the formation of potassium chloride.

There is no separation of underlyes in potash soap, consequently the product contains the whole constituents of the oils used, as the operation of salting out is quite impracticable owing to the double decomposition which results from the action of salt, producing thereby a hard principally soda soap with formation of potassium chloride.

Soft or green soap (potassium oleate), made by acting on olive oil with caustic potash, is also used; its preparation (Linamentum saponis) is known as opodeldoc. Curd soap is also used, and is chiefly a stearate of sodium.

Potassium, when heated, burns in the vapour of carbon bisulphide, forming potassium sulphide and liberating carbon.

Carbon bisulphide slowly oxidizes on exposure to air, but by the action of potassium permanganate or chromic acid it is readily oxidized to carbon dioxide and sulphuric acid.

These are washed with ammonium chloride until the filtrate is colourless, ignited, fused with caustic potash and nitre, the melt dissolved in water and nitric acid added to the solution until the colour of potassium ruthenate disappears.

Fusion with caustic potash converts it into a mixture of potassium ruthenate and ruthenium sesquioxide, Ru 2 0 3, which is a black, almost insoluble powder.

The peroxide, Ru04, is formed when a solution of potassium ruthenate is decomposed by chlorine, or by oxidizing ruthenium compounds with potassium chlorate and hydrochloric acid, or with potassium permanganate and sulphuric acid.

Potassium ruthenium cyanide, K4Ru(CN) 6.3H 2 O, formed when potassium ruthenate is boiled with a solution of potassium cyanide, crystallizes in colourless plates which are soluble in water.

Potassium ruthenate, K2Ru04 H20, obtained by fusion of the metal with caustic potash and nitre, crystallizes in prisms which become covered with a black deposit on exposure to moist air.

Thus copper sulphate was CuO+S0 3, potassium sulphate 2S0 3 +P00 2 (the symbol Po for potassium was subsequently discarded in favour of K from kalium).

The combination, as it is ordinarily termed, of chlorine with hydrogen, and the displacement of iodine in potassium iodide by the action of chlorine, may be cited as examples; if these reactions are represented, as such reactions very commonly are, by equations which merely express the relative weights of the bodies which enter into reaction, and of the products, thus Cl = HC1 Hydrogen.

For example, when a solution of a ferric salt is added to a solution of potassium thiocyanate, a deep red coloration is produced, owing to the formation of ferric thiocyanate.

The manufacture of glass, also practised in Egypt, demanded a knowledge of sodium or potassium carbonates; the former occurs as an efflorescence on the shores of certain lakes; the latter was obtained from wood ashes.

In particular, the salts of potassium, sodium and ammonium were carefully investigated, but sodium and potassium salts were rarely differentiated.

In the same year as Klaproth detected uranium, he also isolated zirconia or zirconium oxide from the mineral variously known as zircon, hyacinth, jacynth and jargoon; but he failed to obtain the metal, this being first accomplished some years later by Berzelius, who decomposed the double potassium zirconium fluoride with potassium.

In 1808 Davy isolated sodium and potassium; he then turned his attention to the preparation of metallic calcium, barium, strontium and magnesium.

At the same time Berzelius obtained the element, in an impure condition, by fusing silica with charcoal and iron in a blast furnace; its preparation in a pure condition he first accomplished in 1823, when he invented the method of heating double potassium fluorides with metallic potassium.

In 1824 he obtained zirconium from potassium zirconium fluoride; the preparation of (impure) titanium quickly followed, and in 1828 he obtained thorium.

Balard completed for many years Berzelius's group of " halogen " elements; the remaining member, fluorine, notwithstanding many attempts, remained unisolated until 1886, when Henri Moissan obtained it by the electrolysis of potassium fluoride dissolved in hydrofluoric acid.

Serullas and Roscoe; Davy and Stadion investigated chlorine peroxide, formed by treating potassium chlorate with sulphuric acid.

Davy also described and partially investigated the gas, named by him " euchlorine," obtained by heating potassium chlorate with hydrochloric acid; this gas has been more recently examined by Pebal.

Within two years of the invention the authors announced the discovery of two metals, rubidium and caesium, closely allied to sodium, potassium and lithium in properties, in the mineral lepidolite and in the Diirkheim mineral water.

The same methyl iodide gave with potassium cyanide, acetonitril, which was hydrolysed to acetic acid; this must be C(Coch) a H b H c H d.

Thus potassium ortho-oxybenzoate is converted into the salt of para-oxybenzoic acid at 220 0; the three bromphenols, and also the brombenzenesulphonic acids, yield m-dioxybenzene or resorcin when fused with potash.