Humanity has been familiar with potassium for more than a century and a half. In a lecture given in London on November 20, 1807, Humphry Davy reported that by electrolysis of caustic potassium he obtained “small balls with a strong metallic luster... Some of them immediately after their formation burned out with an explosion.” This was potassium.
Potassium is a wonderful metal. It is remarkable not only because it can be cut with a knife, floats in water, flares up with an explosion and burns, turning the flame purple. And not only because this element is one of the most chemically active. All this can be considered natural, because it corresponds to the position of the alkali metal potassium in the periodic table. Potassium is remarkable for its indispensability to all living things and is notable as an all-around “odd” metal.
Please note: its atomic number is 19, atomic mass is 39, there is one electron in the outer electron layer, and its valence is 1+. According to chemists, this explains the exceptional mobility of potassium in nature. It is part of several hundred minerals. It is found in soil, in plants, in the bodies of people and animals. He is like a classic Figaro: here, there, everywhere.
Potassium and soil
It is hardly possible to explain by chance or the whim of linguists the fact that in the Russian language one word denotes both our planet itself and its upper layer - soil. “Mother Earth”, “nurse Earth” is more about the soil than about the planet as a whole...
But what is soil?
An independent and very unique natural body. It is formed from the surface layers of various rocks under the influence of air, water, temperature changes, and the life activity of all kinds of inhabitants of the Earth. Below, under the soil, are hidden the so-called parent rocks, composed of various minerals. They are gradually destroyed and replenish the “reserves” of the soil.
And in the soil, in addition to purely mechanical, other destruction is constantly occurring. It is called chemical weathering. Water and carbon dioxide (to a lesser extent other substances) gradually destroy minerals.
Almost 18% of the weight of the earth's crust comes from the potassium-containing mineral orthoclase. This is a double salt of silicic acid K 2 Al 2 Si 6 O 16 or K 2 O · Al 2 O 3 · 6SiO 2. Here's what happens to orthoclase as a result of chemical weathering:
K 2 O · Al 2 O 3 · 6SiO 2 + 2H 2 O + CO 2 → K 2 CO 3 + Al 2 O 3 · 2SiO 2 · 2H 2 O + 4SiO 2 .
Orthoclase turns into kaolin (a type of clay), sand and potash. Sand and clay are used to build the mineral backbone of the soil, and potassium, transferred from orthoclase to potash, is “liberated” and becomes available to plants. But not all at once.
In soil waters, K 2 CO 3 molecules dissociate: K 2 CO 3 ↔ K + + KCO – 3 ↔ 2K + + CO 2– 3 . Some potassium ions remain in the soil solution, which serves as a source of nutrition for plants. But most of the potassium ions are absorbed by colloidal soil particles, from where it is quite difficult for plant roots to extract them. So it turns out that, although there is a lot of potassium in the soil, plants often do not have enough of it.
Due to the fact that soil lumps “lock up” most of the potassium, the content of this element in sea water is almost 50 times less than sodium. It is estimated that of the thousand potassium atoms released by chemical weathering, only two reach marine basins, and 998 remain in the soil. “The soil absorbs potassium, and this is its miraculous power,” wrote academician A.E. Fersman.
Potassium and plant
Potassium is found in all plants. Lack of potassium leads to the death of the plant. Almost all potassium is found in plants in the ionic form - K +. Some of the ions are in the cell sap, the other part is absorbed by the structural elements of the cell.
Potassium ions are involved in many biochemical processes occurring in the plant. It has been established that in plant cells these ions are found mainly in the protoplasm. They are not found in the cell nucleus. Consequently, potassium is not involved in the processes of reproduction and the transmission of hereditary characteristics. But even without this, the role of potassium in the life of a plant is great and diverse.
Potassium is included in fruits, roots, stems, and leaves, and in vegetative organs there is, as a rule, more of it than in fruits. Another characteristic feature: young plants contain more potassium than old ones. It has also been noted that as individual plant organs age, potassium ions move to the points of most intensive growth.
With a lack of potassium, plants grow more slowly, their leaves, especially old ones, turn yellow and turn brown at the edges, the stem becomes thin and fragile, and the seeds lose their viability.
It has been established that potassium ions activate the synthesis of organic substances in plant cells. They have a particularly strong influence on the processes of carbohydrate formation. If there is not enough potassium, the plant absorbs carbon dioxide worse, and it lacks carbon “raw materials” for the synthesis of new carbohydrate molecules. At the same time, respiration processes intensify, and the sugars contained in the cell sap are oxidized. Thus, the reserves of carbohydrates in plants that find themselves on a starvation diet (potassium) are not replenished, but consumed. The fruits of such a plant - this is especially noticeable in fruits - will be less sweet than those of plants that received a normal dose of potassium. Starch is also a carbohydrate, so its content in fruits is greatly influenced by potassium.
But that's not all. Plants that receive enough potassium tolerate drought and frosty winters more easily. This is explained by the fact that potassium affects the ability of colloidal substances in plant cells to absorb water and swell. There is not enough potassium - cells absorb and retain moisture worse, shrink, and die.
Potassium ions also affect nitrogen metabolism. When there is a lack of potassium, excess ammonia accumulates in the cells. This can lead to poisoning and death of the plant.
It has already been mentioned that potassium also affects plant respiration, and increased respiration affects not only the carbohydrate content. The more intense the respiration, the more active all oxidative processes are, and many organic substances are converted into organic acids. Excess acids can cause protein breakdown. The products of this decay are a very favorable environment for fungi and bacteria. That is why, during potassium starvation, plants are much more often affected by diseases and pests. Fruits and vegetables containing protein breakdown products do not tolerate transportation well and cannot be stored for a long time.
In a word, if you want to get tasty and well-preserved fruits, feed the plant plenty of potassium. And for grains, potassium is important for one more reason: it increases the strength of the straw and thereby prevents lodging of the grain...
Potash fertilizers
Plants extract large amounts of potassium from the soil every year.
The cheapest (actually free) and at the same time excellent quality potassium fertilizer is stove ash. It contains potassium in the form of potash K 2 CO 3 . The composition of the ash of different plants is far from the same. The most potassium is in sunflower ash - 36.3% K 2 O (the potassium content in potash fertilizers is usually converted to K 2 O). There is significantly less potassium oxide in firewood ash - from 3.2% (spruce firewood) to 13.8% (birch firewood). There is even less potassium in peat ash.
Of course, ash alone cannot satisfy the potassium hunger of plants. The most important potash fertilizers were natural potassium salts, primarily sylvinite and kainite. Sylvinite is a very common mineral. Its composition is indicated by the formula m KCl n NaCl. In addition to sodium and potassium chlorides, it contains impurities of calcium, magnesium and other elements. Usually in sylvinite there is 14...18% K 2 O. In kainite KCl · MgSO 4 · 3H 2 O there is less potassium oxide - 10...12%.
A significant part of natural potassium salts is processed into a technical product - potassium chloride (potassium content in terms of K 2 O 50...62%).
Potassium chloride is obtained from sylvinite using halurgy or flotation methods. The first is based on the different solubility of KCl and NaCl in water at elevated temperatures. The second is on the different wettability of these substances.
The first method is used more widely. At normal temperatures, the solubility of potassium and sodium chlorides is almost the same. With increasing temperature, the solubility of NaCl remains almost unchanged, but the solubility of KCl increases greatly. A saturated solution of both salts is prepared in the cold, then it is heated and sylvinite is treated with it. In this case, the solution is additionally saturated with potassium chloride, and part of the table salt is displaced from the solution, precipitates and is separated by filtration. The solution is cooled and excess potassium chloride crystallizes out of it. The crystals are separated in centrifuges and dried, and the mother liquor is used to process a new portion of sylvinite.
Technical potassium chloride is used both independently and in mixture with natural potassium salts.
The more expensive, but non-hygroscopic and non-caking potassium sulfate K2SO4 is also used as a fertilizer. This fertilizer can be used on any soil. And chlorine ions introduced by potassium chloride are clearly undesirable for some soils. They are also contraindicated for some plants. An excess of Cl ions reduces the starch content in potato tubers, deteriorates the quality of flax fibers, and makes peaches, grapes and citrus fruits more sour.
Thus, by fertilizing the earth with potassium chloride, we simultaneously do everything to improve and... worsen the quality of future fruits. The latter can be avoided if you use the most rational, chemically based methods of adding potassium salts.
Chlorine ions, unlike potassium ions, are not absorbed by the soil: they are easily washed out by groundwater and carried into the lower horizons. Therefore, in order to retain potassium in the soil, but remove chlorine from it, it is necessary to apply chlorine-containing potassium fertilizers to the soil in the fall. While the seeds germinate and the root system begins to absorb ions from the soil, autumn rains and meltwater will have time to carry chlorine ions deeper.
By the way, any potash fertilizer should not just be scattered evenly across the field, but should be incorporated with a plow to the plowing depth - this is much more effective.
In agricultural practice, it is customary to apply from 30 to 90 kg of K 2 O per hectare of crops. But these doses are very conditional, since the need for potassium fertilizers is determined not only by the composition of the soil, but also by what crop is sown in this field. Beets, potatoes, legumes, sunflowers, and buckwheat need more potassium than wheat, rye, and barley.
Agronomists believe that, under favorable conditions, one kilogram of K 2 O on average gives the following yield increases: grain - from 3 to 8 kg, potatoes - 35 kg, sugar beets - 40 kg.
Our country has the world's richest deposits of potassium salts (Solikamsk - Bereznyakov region). In 1975, the country's agriculture received more than 12 million tons of potash fertilizers. This is 12 times more than in 1950 and 2.6 times more than in 1965.
Potassium - for humans
Actually, everything described above is also on the topic of “potassium for humans.” And here, briefly, about the biological role of element No. 19 in the life of the most complex living organism on Earth.
It has been established that potassium salts cannot be replaced in the human body by any other salts. Potassium is mainly found in the blood and protoplasm of cells. The liver and spleen are rich in potassium. The role of this element in regulating the activity of enzymes is significant.
We must not forget about another role of potassium in our life. Natural potassium consists of three isotopes: two stable isotopes - 39 K and 41 K and one radioactive - 40 K with a half-life of about 1.3 billion years. This isotope is found in living organisms and its radiation makes a significant contribution to the total amount of natural (background) radiation...
A child’s body, like a young plant, requires more potassium than an adult’s body. The daily potassium requirement for a child is 12...13 mg per 1 kg of weight, and for an adult – 2...3 mg, i.e. 4...6 times less.
A person gets most of the potassium he needs from foods of plant origin. Potassium deficiency affects various systems and organs, as well as metabolism.
Apparently, Alexander Evgenievich Fersman, who wrote in one of his books: “potassium is the basis of life,” was not exaggerating much.
Meeting potassium?
If in a warehouse or freight station you see steel boxes with the inscriptions: “Flammable!”, “Water Explodes,” then it is very likely that you have encountered potassium.
Many precautions are taken when transporting this metal. Therefore, when you open a steel box, you will not see potassium, but you will see carefully sealed steel cans. They contain potassium and inert gas - the only environment safe for potassium. Large quantities of potassium are transported in sealed containers under an inert gas pressure of 1.5 atm.
Why is potassium metal needed?
Potassium metal is used as a catalyst in the production of certain types of synthetic rubber, as well as in laboratory practice. Recently, the main use of this metal has been the production of potassium peroxide K 2 O 2, used for oxygen regeneration. An alloy of potassium with sodium serves as a coolant in nuclear reactors, and in the production of titanium as a reducing agent.
From salt and alkali
Potassium is most often obtained in the exchange reaction of molten potassium hydroxide and metallic sodium: KOH + Na → NaOH + K. The process takes place in a nickel distillation column at a temperature of 380...440°C. Element No. 19 is also obtained from potassium chloride in a similar way, only in this case the process temperature is higher - 760...800°C. At this temperature, both sodium and potassium turn into steam, and potassium chloride (with additives) melts. Sodium vapor is passed through molten salt and the resulting potassium vapor is condensed. Sodium-potassium alloys are also prepared using the same method. The composition of the alloy largely depends on the process conditions.
What if...
This is your first time dealing with potassium metal.
It is necessary to remember the high reactivity of this metal, that potassium ignites from the slightest trace of water. When working with potassium, be sure to wear rubber gloves and safety glasses, or better yet, a mask that covers the entire face. Large quantities of potassium are worked in special chambers filled with nitrogen or argon. (In special spacesuits, of course.)
And if potassium does ignite, it is extinguished not with water, but with soda or table salt.
Are there potassium ions in the solution?
It's not difficult to find out. Dip the wire ring into the solution, and then place it in the flame of a gas burner. If there is potassium, the flame will turn purple, although not as bright as the yellow color given to the flame by sodium compounds.
It is more difficult to determine how much potassium is in the solution. This metal has few water-insoluble compounds. Typically, potassium is precipitated in the form of perchlorate - a salt of very strong perchloric acid HClO 4. By the way, potassium perchlorate is a very strong oxidizing agent and as such is used in the production of some explosives and rocket fuels.
What is potassium cyanide used for?
For extracting gold and silver from ores. For galvanic gilding and silvering of base metals. For obtaining many organic substances. For nitriding steel - this gives its surface greater strength.
Unfortunately, this much-needed substance is extremely poisonous. And KCN looks quite harmless: small white crystals with a brownish or gray tint.
What is Chrompeak?
More precisely, potassium chromium. These are orange crystals of the composition K 2 Cr 2 O 7. Chrompic is used in the production of dyes, and its solutions are used for “chrome” tanning of leather, as well as as a mordant for dyeing and printing fabrics. A solution of chromium in sulfuric acid is a chromic mixture that is used in all laboratories for washing glassware.
Why do you need caustic potassium?
Really, why? After all, the properties of this alkali and the cheaper caustic soda are almost the same. Chemists discovered the difference between these substances only in the 18th century. The most noticeable difference between NaOH and KOH is that potassium hydroxide is even more soluble in water than sodium hydroxide. KOH is obtained by electrolysis of potassium chloride solutions. To keep the chloride admixture to a minimum, mercury cathodes are used. But this substance is needed primarily as a starting product for the production of various potassium salts. In addition, caustic potassium is indispensable in the production of liquid soaps, some dyes and organic compounds. Caustic potassium solution is used as an electrolyte in alkaline batteries.
Saltpeter or saltpeter?
More correctly - saltpeter. This is the general name for nitrate salts of alkali and alkaline earth metals. If they simply say “saltpeter” (not “sodium” or “calcium” or “ammonium”, but simply “saltpeter”), then they mean potassium nitrate. Humanity has been using this substance for more than a thousand years to produce black powder. In addition, saltpeter is the first double fertilizer: of the three most important elements for plants, it contains two - nitrogen and potassium. This is how D.I. described saltpeter. Mendeleev in “Fundamentals of Chemistry”:
“Saltpeter is a colorless salt that has a special cooling taste. It easily crystallizes into long, grooved, rhombic, hexagonal prisms on the sides, ending in the same pyramids. Its crystals (specific gravity 1.93) do not contain water. At low heat (339°), saltpeter melts into a completely colorless liquid. At ordinary temperatures, in solid form, KNO 3 is inactive and unchanged, but at elevated temperatures it acts as a very strong oxidizing agent, because it can release a significant amount of oxygen to substances mixed with it. Nitre thrown onto hot coal produces rapid combustion, and its mechanical mixture with crushed coal ignites upon contact with a hot body and continues to burn by itself. In this case, nitrogen is released, and the oxygen of the nitrate goes to the oxidation of coal, as a result of which carbonic potassium salt (Meaning potash) and carbon dioxide are obtained...
In chemical practice and technology, saltpeter is used in many cases as an oxidizing agent that acts at high temperatures. This is also the basis for its use for ordinary gunpowder, which is a mechanical mixture of finely ground sulfur, saltpeter and coal.”
Where and for what are other potassium salts used?
Potassium bromide KBr - in photography to protect the negative or print from being veiled.
Potassium iodide KI - in medicine and as a chemical reagent. Potassium fluoride KF - in metallurgical fluxes and for introducing fluorine into organic compounds.
Potassium carbonate (potash) K 2 CO 3 - in glass and soap production, as well as kick fertilizer.
Potassium phosphates, in particular K 4 R 2 O 7 and K 5 R 3 O 10, are used as components of detergents.
Potassium chlorate (Berthollet salt) KClO 3 – in match production and pyrotechnics.
Potassium silicofluoride K 2 SiF 6 – as an additive to the charge when extracting rare earth elements from minerals.
Potassium iron sulfide (yellow blood salt) K 4 Fe(CN) 6 3H 2 O - as a mordant for dyeing fabrics and in photography.
Why is potassium called potassium?
The word is of Arabic origin. In Arabic, al-kali means plant ash. For the first time, potassium was obtained from caustic potassium, and caustic potash was obtained from potash isolated from plant ash... However, in English and other European languages the name potassium was preserved, given to potassium by its discoverer X. Davy. As you might guess, this word originates from the word “potash”.
The name “potassium” was introduced into Russian chemical nomenclature in 1831 by G.I. Hessom.
DEFINITION
Potassium- the nineteenth element of the periodic table. Designation - K from the Latin "kalium". Located in the fourth period, group IA. Refers to metals. The nuclear charge is 19.
Potassium does not occur in nature in a free state. The most important potassium minerals are: sylvite KCl, sylvinite NaCl×KCl, carnallite KCl×MgCl 2 ×6H 2 O, kainite KCl×MgSO 4 ×3H 2 O.
In its simple form, potassium is a shiny silver-gray metal (Figure 1) with a body-centered crystal lattice. An exceptionally reactive metal: it quickly oxidizes in air, forming loose reaction products.
Rice. 1. Potassium. Appearance.
Atomic and molecular mass of potassium
Relative molecular mass of the substance (Mr) is a number showing how many times the mass of a given molecule is greater than 1/12 the mass of a carbon atom, and relative atomic mass of an element(A r) - how many times the average mass of atoms of a chemical element is greater than 1/12 of the mass of a carbon atom.
Since in the free state potassium exists in the form of monatomic K molecules, the values of its atomic and molecular masses coincide. They are equal to 39.0983.
Potassium isotopes
It is known that in nature potassium can be found in the form of two stable isotopes 39 K and 41 K. Their mass numbers are 39 and 41, respectively. The nucleus of an atom of the 39 K potassium isotope contains nineteen protons and twenty neutrons, and the 41 K isotope contains the same number of protons and twenty-two neutrons.
There are artificial isotopes of potassium with mass numbers from 32 to 55, among which the most stable is 40 K with a half-life of 1.248 × 10 9 years.
Potassium ions
At the outer energy level of the potassium atom there is one electron, which is a valence electron:
1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 .
As a result of chemical interaction, potassium gives up its only valence electron, i.e. is its donor, and turns into a positively charged ion:
K 0 -1e → L + .
Potassium molecule and atom
In the free state, potassium exists in the form of monatomic molecules L. Let us present some properties characterizing the potassium atom and molecule:
Examples of problem solving
EXAMPLE 1
EXAMPLE 2
| Exercise | Calculate the mass of potassium hydroxide required to prepare a 20 ml alkali solution (mass fraction of KOH 20%, density 1.22 g/ml). |
| Solution | Let's find the mass of the potassium hydroxide solution: In nature, potassium is found only in combination with other elements, for example, in sea water, and also in many minerals. It oxidizes very quickly in air and very easily enters into chemical reactions, especially with water, forming an alkali. In many properties, potassium is very close to sodium, but from the point of view of biological function and use by the cells of living organisms, they are antagonistic. History and origin of the namePotassium compounds have been used since ancient times. Thus, the production of potash (which was used as a detergent) existed already in the 11th century. The ash formed when burning straw or wood was treated with water, and the resulting solution (lye) was evaporated after filtering. The dry residue, in addition to potassium carbonate, contained potassium sulfate K2SO4, soda and potassium chloride KCl. Place of BirthThe largest potash deposits are located in Canada (manufacturer PotashCorp), Russia (PJSC "Uralkali", Berezniki, Solikamsk, Perm Territory, Verkhnekamskoye potassium ore deposit), Belarus (PO "Belaruskali", Soligorsk, Starobinskoye potash deposit ore). ReceiptPotassium, like other alkali metals, is obtained by electrolysis of molten chlorides or alkalis. Since chlorides have a higher melting point (600-650 °C), electrolysis of molten alkalis is more often carried out with the addition of soda or potash (up to 12%). During the electrolysis of molten chlorides, molten potassium is released at the cathode, and chlorine is released at the anode: K + + e − → K (\displaystyle (\mathsf (K^(+)+e^(-)\rightarrow K))) 2 C l − → C l 2 (\displaystyle (\mathsf (2Cl^(-)\rightarrow Cl_(2))))During the electrolysis of alkalis, molten potassium is also released at the cathode, and oxygen at the anode: 4 O H − → 2 H 2 O + O 2 (\displaystyle (\mathsf (4OH^(-)\rightarrow 2H_(2)O+O_(2))))The water from the melt evaporates quickly. To prevent potassium from interacting with chlorine or oxygen, the cathode is made of copper and a copper cylinder is placed above it. The resulting potassium is collected in molten form in a cylinder. The anode is also made in the form of a cylinder from nickel (for electrolysis of alkalis) or from graphite (for electrolysis of chlorides). Thermochemical reduction methods are also of industrial importance: N a + K O H → N 2 380 − 450 o C N a O H + K (\displaystyle (\mathsf (Na+KOH(\xrightarrow[(N_(2))](380-450^(o)C))NaOH+ K)))and reduction of potassium chloride from the melt with calcium carbide, aluminum or silicon. Physical propertiesPotassium is a silvery metal with a characteristic shine on a freshly formed surface. Very light and fusible. It dissolves relatively well in, forming amalgams. When introduced into the burner flame, potassium (as well as its compounds) colors the flame a characteristic pink-violet color. Interaction with simple substancesPotassium at room temperature reacts with atmospheric oxygen and halogens; practically does not react with nitrogen (unlike lithium and sodium). When heated moderately, it reacts with hydrogen to form a hydride (200-350 °C): 2 K + H 2 ⟶ 2 K H (\displaystyle (\mathsf (2K+H_(2)\longrightarrow 2KH))) 2 K + 2 N H 3 ⟶ 2 K N H 2 + H 2 (\displaystyle (\mathsf (2K+2NH_(3)\longrightarrow 2KNH_(2)+H_(2))))Potassium metal reacts with alcohols to form alcoholates: 2 K + 2 C 2 H 5 O H ⟶ 2 C 2 H 5 O K + H 2 (\displaystyle (\mathsf (2K+2C_(2)H_(5)OH\longrightarrow 2C_(2)H_(5)OK+H_ (2)\uparrow )))Alcoholates of alkali metals (in this case, potassium ethanolate) are very strong bases and are widely used in organic synthesis. Oxygen compoundsK + O 2 ⟶ K O 2 (\displaystyle (\mathsf (K+O_(2)\longrightarrow KO_(2))))Potassium oxide can be obtained by heating the metal to a temperature not exceeding 180 °C in an environment containing very little oxygen, or by heating a mixture of potassium superoxide with potassium metal: K O 2 + 3 K ⟶ 2 K 2 O (\displaystyle (\mathsf (KO_(2)+3K\longrightarrow 2K_(2)O)))Potassium oxides have pronounced basic properties and react violently with water, acids and acid oxides. They have no practical significance. Peroxides are yellowish-white powders that, soluble in water, form alkalis and hydrogen peroxide: K 2 O 2 + 2 H 2 O ⟶ 2 K O H + H 2 O 2 (\displaystyle (\mathsf (K_(2)O_(2)+2H_(2)O\longrightarrow 2KOH+H_(2)O_(2) ))) 4 K O 2 + 2 H 2 O ⟶ 4 K O H + 3 O 2 (\displaystyle (\mathsf (4KO_(2)+2H_(2)O\longrightarrow 4KOH+3O_(2)\uparrow ))) 4 K O 2 + 2 C O 2 ⟶ 2 K 2 C O 3 + 3 O 2 (\displaystyle (\mathsf (4KO_(2)+2CO_(2)\longrightarrow 2K_(2)CO_(3)+3O_(2)\uparrow )))The ability to exchange carbon dioxide for oxygen is used in insulating gas masks and on submarines. An equimolar mixture of potassium superoxide and sodium peroxide is used as an absorber. If the mixture is not equimolar, then in the case of an excess of sodium peroxide, more gas will be absorbed than released (when absorbing two volumes of CO 2, one volume of O 2 is released), and the pressure in a confined space will drop, and in the case of an excess of potassium superoxide (when absorbing two volumes of CO 2 three volumes of O are released 2) more gas is released than absorbed, and the pressure will increase. In the case of an equimolar mixture (Na 2 O 2:K 2 O 4 = 1:1), the volumes of absorbed and released gases will be equal (when four volumes of CO 2 are absorbed, four volumes of O 2 are released). Peroxides are strong oxidizing agents, so they are used to bleach fabrics in the textile industry. Peroxides are obtained by calcining metals in air freed from carbon dioxide. Also known is potassium ozonide KO 3, orange-red in color. It can be obtained by reacting potassium hydroxide with ozone at a temperature not exceeding 20 °C: 4 K O H + 4 O 3 ⟶ 4 K O 3 + O 2 + 2 H 2 O (\displaystyle (\mathsf (4KOH+4O_(3)\longrightarrow 4KO_(3)+O_(2)+2H_(2)O)) )Potassium ozonide is a very strong oxidizing agent, for example, it oxidizes elemental sulfur to sulfate and disulfate already at 50 °C: 6 K O 3 + 5 S ⟶ K 2 S O 4 + 2 K 2 S 2 O 7 (\displaystyle (\mathsf (6KO_(3)+5S\longrightarrow K_(2)SO_(4)+2K_(2)S_(2 )O_(7))))HydroxidePotassium hydroxide (or caustic potassium) are hard white opaque, very hygroscopic crystals that melt at a temperature of 360 °C. Potassium hydroxide is an alkali. It dissolves well in water and releases a large amount of heat. The solubility of potassium hydroxide at 20 °C in 100 g of water is 112 g. Application
Important Connections
Biological rolePotassium is the most important biogenic element, especially in the plant world. If there is a lack of potassium in the soil, plants develop very poorly, the yield decreases, therefore about 90% of the extracted potassium salts are used as fertilizers. Denoted by the Latin letter K (from the Latin Kalium). Some potassium compounds (for example, potash, extracted from wood ash) were already known in antiquity; however, potassium itself was discovered only in 1807 by the English chemist Humphry Davy, who named the new chemical element “potassium” (in consonance with the already known potash - potassium carbonate K 2 CO 3). In 1809, the German scientist Ludwig Wilhelm Hilbert proposed the name “potassium” (from the Arabic al-kali - potash), which successfully took root. Potassium is of great importance for human health, even small changes in potassium content in the body can affect its normal functioning. Let's look at why potassium is needed in the human body, why is its deficiency dangerous and, conversely, its excess concentration? Morning has come for everyone, but not for you? There's a rush at work, and you're tired and your nerves are on edge? You need to cheer yourself up, of course, only coffee can help you out. The work day has ended, but your mood still hasn’t improved? Do you think you can resort to alcohol to get rid of a dashing mood, and eat it with chocolate? Then the question is – how do you feel? Are you worried about nerves and general fatigue? Yes, caffeine invigorates you. But for how long? The problem has already been identified - the body is undermined by the abuse of sweets, physical activity and alcoholic beverages. As a result, such a valuable microelement as potassium is lost, which keeps our muscles toned, gives us vigor and ensures a good mood. This does not happen “suddenly”. Coffee and all diuretic drinks simply wash this trace element out of the body, alcohol and sugar-containing products slow down its absorption. Symptoms of potassium deficiency in the bodyIf a bruise appears on the body from minor touches, hitherto unknown painful sensations begin to appear in the muscles - this is also a decrease in the presence of potassium in the body. You can get rid of the disease for a while thanks to the nutritional composition, in a 1:1 ratio, of honey and apple cider vinegar. By rubbing this solution into sore muscles, due to the well-absorbed vinegar, the tissues are supplied with potassium. Potassium deficiency can also include symptoms such as causeless cramps and the appearance of bursting small blood vessels. If you want to feel healthy, learn as much as possible about this microelement. At the first symptoms of the disease, many people run to the pharmacy. But without the advice of a specialist, it is better not to take any measures. To treat potassium deficiency in the body, it is necessary to have a detailed blood test, since excess potassium in the body contributes to more severe diseases than its deficiency. Hyperkalemia is dangerous to health. Dehydration, stomach upset, drowsiness, arrhythmia, and loss of orientation may occur. This condition occurs when taking antitumor and some anti-inflammatory drugs. Only a doctor prescribes treatment and gives recommendations on the consumption of necessary foods. If you want not to burden the people close to you with your health problems, take potassium-containing products. Potassium in foodThere is a wonderful recipe that allows you to increase the potassium content in the body, which was known to our grandmothers - in the morning on an empty stomach, drink a teaspoon of honey diluted in a glass of boiled water. Today it has been improved. Now it is recommended to drink the same amount of boiled water, but with the addition of one teaspoon each of bee honey and apple cider vinegar, since potassium is found in the greatest quantities in these products. It is recommended to take this drink throughout the day, before each meal, in small sips. Potassium content exists in significant quantities not only in apple cider vinegar and honey, but also in wheat bran and yeast. Depending on physical activity and body weight, the daily amount of potassium for each person is highly individual. It is not difficult to maintain it if you eat the appropriate foods. Potassium is found in both meat and plant products and is a component of all plants and animals. All marine organisms obtain potassium from water. Fruit trees, nuts, vegetable and cereal plants extract it from the soil. How to replenish the body with potassium, having learned to understand the products with this invaluable mineral? We divide them into a plant group and an animal group. From the plant world, walnuts and cashews are inferior to their fellow dried apricots, raisins and prunes. In dried fruits, raisins, figs and the same prunes take the lead. To maintain the daily amount of potassium in the body in the summer, it is enough to include vegetables and herbs in the diet. Fresh berries, radishes, tomatoes, cucumbers, carrots, and zucchini should be preferred over canned foods. We must remember that potassium is retained for a long time in vegetables and fruits - it is advisable to wash and peel them before use. Potatoes, steamed or baked in the oven, will be healthier than boiled ones. Do not leave cut fruits and vegetables for a long time - in this form they quickly lose potassium. To enrich the body with potassium, it is advisable to use fruits: melons, oranges, bananas, watermelons, and you can diversify the menu by preparing berry-fruit cocktails, fresh juices, and purees from them. In winter, animal products will help support the body with potassium: cottage cheese, liver, fish and all other meat and dairy products. To normalize the acid-base balance, maintain water balance and normalize the osmotic concentration of blood in the human body, potassium is always functionally linked to sodium and magnesium. Only in this way will the heart work without disturbances, the brain will receive enough oxygen and fatigue and chronic fatigue will disappear. In a word, don’t wait for the alarm bell to ring warning of a malfunction in the body, take care of yourself in advance. (Kalium) K, chemical element 1 (Ia) of group of the Periodic table, belongs to the alkaline elements. Atomic number 19, atomic mass 39.0983. It consists of two stable isotopes 39 K (93.259%) and 41 K (6.729%), as well as a radioactive isotope 40 K with a half-life of ~10 9 years. This isotope plays a special role in nature. Its share in the mixture of isotopes is only 0.01%, but it is the source of almost all argon 40 Ar contained in the earth's atmosphere, which is formed during the radioactive decay of 40 K. In addition, 40 K is present in all living organisms, which may has a certain influence on their development. The 40 K isotope is used to determine the age of rocks using the potassium-argon method. The artificial isotope 42 K with a half-life of 15.52 years is used as a radioactive tracer in medicine and biology. Oxidation state +1. Potassium compounds have been known since ancient times. Potash potassium carbonate K 2 CO 3 has long been isolated from wood ash. Potassium metal was prepared by electrolysis of molten potassium hydroxide (KOH) in 1807 by the English chemist and physicist Humphry Davy. The name "potassium" chosen by Davy reflects the element's origins in potash. The Latin name of the element is derived from the Arabic name for potash “al-kali”. The word “potassium” was introduced into Russian chemical nomenclature in 1831 by St. Petersburg academician Hermann Hess (1802–1850). Figurovsky N.A. Discovery of elements and origin of their names. M., Nauka, 1970 Find " POTASSIUM" on |