Potassium - the nineteenth element of the periodic table of Mendeleev, belongs to the alkali metals. This is a simple substance that under normal conditions is in a solid state of aggregation. Potassium boils at a temperature of 761 °C. The melting point of the element is 63 °C. Potassium has a silvery-white color with a metallic sheen.

Chemical properties of potassium

Potassium - which has a high chemical activity, therefore it cannot be stored in the open air: the alkali metal instantly reacts with surrounding substances. This chemical element belongs to group I and period IV of the periodic table. Potassium has all the characteristic properties of metals.

It interacts with simple substances, which include halogens (bromine, chlorine, fluorine, iodine) and phosphorus, nitrogen and oxygen. The interaction of potassium with oxygen is called oxidation. During this chemical reaction, oxygen and potassium are consumed in a 4:1 molar ratio, resulting in the formation of potassium oxide in the amount of two parts. This interaction can be expressed by the reaction equation:

4K + O₂ \u003d 2K₂O

During the combustion of potassium, a flame of bright purple color is observed.

Such an interaction is considered a qualitative reaction to the determination of potassium. The reactions of potassium with halogens are named according to the names of the chemical elements: these are fluorination, iodination, bromination, chlorination. Such interactions are addition reactions. An example is the reaction between potassium and chlorine, which produces potassium chloride. To carry out such an interaction, two moles of potassium and one mole are taken. As a result, two moles of potassium are formed:

2K + СІ₂ = 2КІ

Molecular structure of potassium chloride

When burning in the open air, potassium and nitrogen are consumed in a molar ratio of 6:1. As a result of this interaction, potassium nitride is formed in the amount of two parts:

6K + N₂ = 2K₃N

The compound is green-black crystals. Potassium reacts with phosphorus in the same way. If you take 3 moles of potassium and 1 mole of phosphorus, you get 1 mole of phosphide:

3K + P = K₃P

Potassium reacts with hydrogen to form a hydride:

2K + N₂ = 2KN

All addition reactions occur at high temperatures

The interaction of potassium with complex substances

Complex substances with which potassium reacts include water, salts, acids, and oxides. Since potassium is an active metal, it displaces hydrogen atoms from their compounds. An example is the reaction between potassium and hydrochloric acid. For its implementation, 2 moles of potassium and acid are taken. As a result of the reaction, 2 moles of potassium chloride and 1 mole of hydrogen are formed:

2K + 2HCI = 2KSI + H₂

In more detail, it is worth considering the process of interaction of potassium with water. Potassium reacts violently with water. It moves on the surface of the water, it is pushed by the released hydrogen:

2K + 2H₂O = 2KOH + H₂

During the reaction, a lot of heat is released per unit time, which leads to the ignition of potassium and the released hydrogen. This is a very interesting process: upon contact with water, potassium instantly ignites, the violet flame crackles and quickly moves along the surface of the water. At the end of the reaction, a flash occurs with splashing of drops of burning potassium and reaction products.

Reaction of potassium with water

The main end product of the reaction of potassium with water is potassium hydroxide (alkali). The equation for the reaction of potassium with water:

4K + 2H₂O + O₂ = 4KOH

Attention! Do not try to repeat this experience yourself!

If the experiment is carried out incorrectly, you can get a burn with alkali. For the reaction, a crystallizer with water is usually used, in which a piece of potassium is placed. As soon as the hydrogen stops burning, many want to look into the crystallizer. At this moment, the final stage of the reaction of potassium with water occurs, accompanied by a weak explosion and splashing of the resulting hot alkali. Therefore, for safety reasons, it is worth keeping some distance from the laboratory table until the reaction is complete. you will find the most spectacular experiences you can have with your kids at home.

The structure of potassium

The potassium atom consists of a nucleus containing protons and neutrons, and electrons revolving around it. The number of electrons is always equal to the number of protons inside the nucleus. When an electron is detached or attached to an atom, it ceases to be neutral and turns into an ion. Ions are divided into cations and anions. Cations have a positive charge, anions have a negative charge. When an electron is attached to an atom, it becomes an anion; if one of the electrons leaves its orbit, the neutral atom turns into a cation.

The serial number of potassium in Mendeleev's periodic table is 19. This means that there are also 19 protons in the nucleus of a chemical element. Conclusion: there are 19 electrons around the nucleus. The number of protons in the structure is determined as follows: subtract the serial number of the chemical element from the atomic mass. Conclusion: there are 20 protons in the potassium nucleus. Potassium belongs to the IV period, has 4 "orbits", on which electrons are evenly distributed, which are in constant motion. On the first "orbit" there are 2 electrons, on the second - 8; on the third and on the last, fourth "orbit", 1 electron rotates. This explains the high level of chemical activity of potassium: its last "orbit" is not completely filled, so the element tends to combine with other atoms. As a result, the electrons of the last orbits of the two elements will become common.

There are three main classes of connections. These are acids, alkalis and oxides. An acid consists of a hydrogen cation and an anion of an acid residue. Alkali - from a metal cation and a hydroxyl group. We will talk about oxides in more detail later.

What is an oxide?

It is a compound made up of two different chemical elements, one of which is oxygen. The second can be metal or non-metal. The number of oxygen atoms depends on the valence of the second chemical element that is part of the compound. So, for example, the valency of potassium is one, so potassium oxide will contain one oxygen atom and two potassium atoms. The valency of calcium is two, so its oxide will consist of one oxygen atom and one calcium atom. The valency of phosphorus is five, so its oxide consists of two phosphorus atoms and five oxygen atoms.

In this article, we will talk in more detail about potassium oxide. Namely - about its physical and chemical properties, about its application in various fields of industry.

Potassium oxide: formula

Since the valence of this metal is one, and the valency of oxygen is two, this chemical compound will consist of two metal atoms and one oxygen atom. So, potassium oxide: the formula is K 2 O.

Physical Properties

The oxide under consideration has a pale yellow color. Sometimes it can also be colorless. At room temperature, it has a solid state of aggregation.

The melting point of this substance is 740 degrees Celsius.

The density is 2.32 g/cm 3 .

Thermal decomposition of this oxide produces peroxide of the same metal and pure potassium.

Soluble in organic solvents.

It does not dissolve in water, but reacts with it.

Possesses high hygroscopicity.

Chemical properties of K 2 O

This substance has chemical properties typical of all basic oxides. Consider the chemical reactions of this oxide with various substances in order.

Reaction with water

First of all, it is able to react with water to form the hydroxide of this metal as a result.

The equation for such a reaction is as follows:

• K 2 O + H 2 O \u003d 2KOH

Knowing the molar mass of each of the substances, the following conclusion can be drawn from the equation: from 94 grams of the oxide in question and 18 grams of water, 112 grams of potassium hydroxide can be obtained.

with other oxides

In addition, the oxide in question is capable of reacting with carbon dioxide (carbon dioxide). This forms a salt - potassium carbonate.

The equation for the reaction of potassium oxide and carbon oxide can be written as follows:

• K 2 O + CO 2 \u003d K 2 CO 3

So, we can conclude that from 94 grams of the oxide in question and 44 grams of carbon dioxide, 138 grams are obtained. potassium carbonate.

The oxide in question can also react with sulfur oxide. In this case, another salt is formed - potassium sulfate.

The interaction of potassium oxide with sulfur oxide can be expressed by the following equation:

• K 2 O + SO 3 \u003d K 2 SO 4

It can be seen from it that by taking 94 grams of the oxide in question and 80 grams of sulfur oxide, 174 grams of potassium sulfate can be obtained.

In the same way, K 2 O can react with other oxides.

Another type of interaction is reactions not with acids, but with amphoteric oxides. In this case, not an acid is formed, but a salt. An example of such a chemical process is the interaction of the considered oxide with zinc oxide.

This reaction can be expressed by the following equation:

• K 2 O + ZnO \u003d K 2 ZnO 2

It can be seen from it that when the oxide in question and zinc oxide interact, a salt is formed called potassium zincate. If you know the molar mass of all substances, then you can calculate that from 94 grams of K 2 O and 81 grams of zinc oxide, you can get 175 grams of potassium zincate.

Also, K 2 O is able to interact with nitric oxide. In this case, a mixture of two salts is formed: potassium nitrate and potassium nitrite. The equation for this reaction looks like this:

• K 2 O + 2NO 2 \u003d KNO 3 + KNO 2

If you know the molar masses of substances, we can say that from 94 grams of the oxide in question and 92 grams of nitrogen oxide, 101 grams of nitrate and 85 grams of nitrite can be obtained.

Interaction with acids

The most common case is potassium oxide + sulfuric acid= potassium sulfate + water. The reaction equation looks like this:

• K 2 O + H 2 SO 4 \u003d K 2 SO 4 + H 2 O

From the equation, we can conclude that to obtain 174 grams of potassium sulfate and 18 grams of water, you need to take 94 grams of the oxide in question and 98 grams of sulfuric acid.

Similarly, there is a chemical interaction between the oxide in question and nitric acid. This produces potassium nitrate and water. The equation for this reaction can be written as follows:

• 2K 2 O + 4HNO 3 \u003d 4KNO 3 + 2H 2 O

Thus, from 188 grams of the oxide in question and 252 grams of nitric acid, 404 grams of potassium nitrate and 36 grams of water can be obtained.

By the same principle, the oxide in question can react with other acids. In the process, other salts and water will be formed. So, for example, when this oxide reacts with phosphoric acid phosphate and water are obtained, with chloride acid - chloride and water, and so on.

K 2 O and halogens

The chemical compound under consideration is also capable of reacting with substances of this group. Halogens are simple compounds consisting of several atoms of the same chemical element. These are, for example, chlorine, bromine, iodine and some others.

So, chlorine and potassium oxide: equation:

• K 2 O + CI 2 \u003d KSI + KSIO

As a result of this interaction, two salts are formed: chloride and potassium hypochlorite. From 94 grams of the oxide in question and 70 grams of chlorine, 74 grams of potassium chloride and 90 grams of potassium hypochlorite are obtained.

Interaction with ammonia

K 2 O is able to react with this substance. As a result of this chemical interaction, potassium hydroxide and amide are formed. The equation for this reaction looks like this:

• K 2 O + NH 3 \u003d KOH + KNH 2

Knowing the molar masses of all substances, it is possible to calculate the proportions of the reactants and reaction products. From 94 grams of the oxide in question and 17 grams of ammonia, 56 grams of potassium hydroxide and 55 grams of potassium amide can be obtained.

Interaction with organic substances

Of the organic chemicals, potassium oxide interacts with ethers and alcohols. However, these reactions are slow and require special conditions.

Getting K 2 O

This chemical can be obtained in several ways. Here are the most common ones:

1. From potassium nitrate and metallic potassium. These two reactants are heated, resulting in the formation of K 2 O and nitrogen. The reaction equation is as follows: 2KNO 3 + 10K = N 2 + 6K 2 O.
2. The second method takes place in two stages. First, a reaction occurs between potassium and oxygen, resulting in the formation of potassium peroxide. The reaction equation looks like this: 2K + O 2 \u003d K 2 O 2. Further, the peroxide is enriched with potassium, as a result of which potassium oxide is obtained. The reaction equation can be written as follows: K 2 O 2 + 2K \u003d 2K 2 O.

The use of K 2 O in industry

The most commonly considered substance is used in the agricultural industry. This oxide is one of the components of mineral fertilizers. Potassium is very important for plants, as it increases their resistance to various diseases. Also, the substance in question is used in construction, as it may be present in the composition of some types of cement. In addition, it is used in the chemical industry to obtain other potassium compounds.

This article will characterize potassium from the point of view of physics and chemistry. The first of these sciences studies the mechanical and external properties of substances. And the second - their interaction with each other - is chemistry. Potassium is the nineteenth element in the periodic table. It belongs to This article will consider the electronic formula of potassium, and its behavior with other substances, etc. This is one of the most active metals. The science that deals with the study of this and other elements is chemistry. Grade 8 provides for the study of their properties. Therefore, this article will be useful for students. So, let's begin.

Characteristics of potassium in terms of physics

This is a simple substance, which under normal conditions is in a solid state of aggregation. The melting point is sixty-three degrees Celsius. This metal boils when the temperature reaches seven hundred and sixty-one degrees Celsius. The substance in question has a silvery-white color. Has a metallic sheen.

The density of potassium is eighty-six hundredths of a gram per cubic centimeter. It is a very light metal. The formula for potassium is very simple - it does not form molecules. This substance consists of atoms that are located close to each other and have a crystal lattice. The atomic mass of potassium is thirty-nine grams per mole. Its hardness is very low - it can be easily cut with a knife, like cheese.

Potassium and chemistry

Let's start with the fact that potassium is a chemical element that has a very high chemical activity. You can’t even store it in the open air, as it instantly begins to react with the substances surrounding it. Potassium is a chemical element that belongs to the first group and the fourth period of the periodic table. It has all the properties that are characteristic of metals.

Interaction with simple substances

These include: oxygen, nitrogen, sulfur, phosphorus, halogens (iodine, fluorine, chlorine, bromine). In order, consider the interaction of potassium with each of them. The interaction with oxygen is called oxidation. During this chemical reaction, potassium and oxygen are consumed in a molar ratio of four parts to one, resulting in the formation of an oxide of the metal in question in the amount of two parts. This interaction can be expressed using the following reaction equation: 4K + O2 = 2K2O. When burning potassium, one can observe

Therefore, this reaction is considered qualitative for the determination of potassium. Reactions with halogens are named according to the names of these chemical elements: these are iodination, fluorination, chlorination, bromination. These interactions can be called addition reactions, since the atoms of two different substances are combined into one. An example of such a process is the reaction between potassium and chlorine, which results in the formation of chloride of the metal in question. To carry out this interaction, it is necessary to take these two components - two moles of the first and one of the second. As a result, two moles of the potassium compound are formed. This reaction is expressed by the following equation: 2K + CI2 = 2KCI. With nitrogen, potassium can form compounds when burned in the open air. During this reaction, the metal in question and nitrogen are consumed in a molar ratio of six parts to one; as a result of this interaction, potassium nitride is formed in an amount of two parts. This can be shown as the following equation: 6K + N2 = 2K3N. This compound is a green-black crystals. With phosphorus, the metal in question reacts according to the same principle. If we take three moles of potassium and one mole of phosphorus, we get one mole of phosphide. This chemical interaction can be written as the following reaction equation: 3K + P = K3P. In addition, potassium is able to react with hydrogen, forming a hydride. As an example, the following equation can be given: 2K + H2 \u003d 2KN. All addition reactions occur only in the presence of high temperatures.

Interaction with complex substances

The characteristic of potassium from the point of view of chemistry provides for the consideration of this topic. Potassium is able to react with water, acids, salts, oxides. With all of them, the metal in question reacts differently.

potassium and water

This chemical element reacts violently with it. In this case, hydroxide is formed, as well as hydrogen. If we take two moles of potassium and water, we get the same amount and one mole of hydrogen. This chemical interaction can be expressed using the following equation: 2K + 2H2O = 2KOH = H2.

Reactions with acids

Since potassium is an active metal, it easily displaces hydrogen atoms from their compounds. An example would be the reaction that occurs between the substance in question and hydrochloric acid. To carry it out, you need to take two moles of potassium, as well as acid in the same amount. As a result, two moles and hydrogen - one mole are formed. This process can be written as follows: 2K + 2HCI = 2KCI + H2.

Potassium and oxides

With this group of inorganic substances, the metal in question reacts only with significant heating. If the atom of the metal that is part of the oxide is more passive than the one we are talking about in this article, an exchange reaction occurs, in fact. For example, if we take two moles of potassium and one mole of cuprum oxide, then as a result of their interaction, one mole of the oxide of the chemical element in question and pure cuprum can be obtained. This can be shown in the form of the following equation: 2K + CuO = K2O + Cu. This is where the strong reducing properties of potassium come into play.

Interaction with bases

Potassium is able to react with metal hydroxides, which are located to the right of it in the electrochemical series of activity. In this case, its restorative properties are also manifested. For example, if we take two moles of potassium and one mole of barium hydroxide, then as a result of the substitution reaction we will get substances such as potassium hydroxide in the amount of two moles and pure barium (one mole) - it will precipitate. The presented chemical interaction can be displayed as the following equation: 2K + Ba(OH)2 = 2KOH + Ba.

Reactions with salts

In this case, potassium still shows its properties as a strong reducing agent. Substituting the atoms of chemically more passive elements, it allows you to get a pure metal. For example, if you add to in the amount of two moles three moles of potassium, then as a result of this reaction we get three moles of potassium chloride and two moles of aluminum. This process can be expressed using an equation as follows: 3К + 2АІСІ3 = 3КІ2 + 2АІ.

Reactions with fats

If potassium is added to any organic substance of this group, it will also displace one of the hydrogen atoms. For example, when stearin is mixed with the metal in question, potassium stearate and hydrogen are formed. The resulting substance is used to make liquid soap. This is where the characterization of potassium and its interactions with other substances ends.

The use of potassium and its compounds

Like all metals, the one discussed in this article is necessary for many industrial processes. The main use of potassium occurs in the chemical industry. Due to its high chemical activity, pronounced alkali metal and reducing properties, it is used as a reagent for many interactions and obtaining a variety of substances. In addition, alloys containing potassium are used as coolants in nuclear reactors. The metal considered in this article also finds its application in electrical engineering. In addition to all of the above, it is one of the main components of fertilizers for plants. In addition, its compounds are used in a wide variety of industries. So, in gold mining, potassium cyanide is used, which serves as a reagent for separating valuable metals from ores. Phosphates of the chemical element under consideration are components of various cleaning products and powders. Matches contain chlorate of this metal. In the manufacture of films for old cameras, the bromide of the element in question was used. As you already know, it can be obtained by brominating potassium at high temperatures. In medicine, chloride of this chemical element is used. In soap making - stearate and other fat derivatives.

Obtaining the metal in question

Nowadays, potassium is mined in laboratories in two main ways. The first is to restore it from hydroxide with the help of sodium, which is chemically even more active than potassium. And the second is getting it from chloride, also with the help of sodium. If you add the same amount of sodium to one mole of potassium hydroxide, one mole of sodium alkali and pure potassium are formed. The equation for this reaction is as follows: KOH + Na = NaOH + K. To carry out the reaction of the second type, you need to mix the chloride of the metal in question and sodium in equal molar proportions. As a result, substances such as kitchen salt and potassium are formed in the same ratio. This chemical interaction can be expressed using the following reaction equation: KSI + Na = NaCl + K.

The structure of potassium

An atom of this chemical element, like all others, consists of a nucleus, which contains protons and neutrons, as well as electrons that revolve around it. The number of electrons is always equal to the number of protons that are inside the nucleus. If any electron detached or joined the atom, then it already ceases to be neutral and turns into an ion. They are of two types: cations and anions. The former are positively charged, while the latter are negatively charged. If an electron joins an atom, then it turns into an anion, but if any of the electrons leaves its orbit, the neutral atom becomes a cation. Since the serial number of potassium, according to the periodic table, is nineteen, there are the same number of protons in the nucleus of this chemical element. Therefore, we can conclude that there are nineteen electrons around the nucleus. The number of protons that are contained in the structure of an atom can be determined by subtracting the serial number of a chemical element from the atomic mass. So we can conclude that there are twenty protons in the potassium nucleus. Since the metal considered in this article belongs to the fourth period, it has four orbits on which electrons are evenly distributed, which are constantly in motion. The scheme of potassium is as follows: two electrons are located in the first orbit, eight in the second; as well as in the third, in the last, fourth, orbit, only one electron rotates. This explains the high level of chemical activity of this metal - its last orbit is not completely filled, so it tends to combine with any other atoms, as a result of which their electrons of the last orbits will become common.

Where can this element be found in nature?

Since it has an extremely high chemical activity, it is not found anywhere on the planet in its pure form. It can only be seen as part of a variety of compounds. potassium in the earth's crust is 2.4 percent. The most common minerals containing potassium are salvinite and carnallite. The first has the following chemical formula: NaCl.KCl. It has a variegated color and consists of many crystals of various colors. Depending on the ratio of potassium chloride and sodium, as well as the presence of impurities, it may contain red, blue, pink, orange components. The second mineral - carnallite - looks like transparent, pale blue, light pink or pale yellow crystals. Its chemical formula looks like this: KCl.MgCl2.6H2O. It is a crystalline hydrate.

The role of potassium in the body, symptoms of deficiency and excess

Together with sodium, it maintains the water-salt balance of the cell. It also participates in the transmission between the membranes of the nerve impulse. In addition, it regulates the acid-base balance in the cell and throughout the body as a whole. It takes part in metabolic processes, counteracts the occurrence of edema, is part of the cytoplasm - about fifty percent of it - the salt of the metal in question. The main signs that the body lacks potassium are swelling, the occurrence of a disease such as dropsy, irritability and disturbances in the functioning of the nervous system, inhibition of the reaction and memory impairment.

In addition, an insufficient amount of this trace element adversely affects the cardiovascular and muscular systems. A lack of potassium for a very long time can provoke a heart attack or stroke. But due to an excess of potassium in the body, an ulcer of the small intestine can develop. To balance your diet in such a way that you get a normal amount of potassium, you need to know what foods contain it.

Foods high in the micronutrient in question

First of all, these are nuts, such as cashews, walnuts, hazelnuts, peanuts, almonds. Also, a large amount of it is found in potatoes. In addition, potassium is found in dried fruits such as raisins, dried apricots, prunes. Pine nuts are also rich in this element. Also, its high concentration is observed in legumes: beans, peas, lentils. Seaweed is also rich in this chemical element. Other products containing this element in large quantities are green tea and cocoa. In addition, it is found in high concentrations in many fruits, such as avocados, bananas, peaches, oranges, grapefruits, and apples. Many cereals are rich in the trace element in question. This is primarily pearl barley, as well as wheat and buckwheat groats. Parsley and Brussels sprouts are also high in potassium. In addition, it is found in carrots and melons. Onions and garlic have a considerable amount of the considered chemical element. Chicken eggs, milk and cheese are also high in potassium. The daily norm of this chemical element for the average person is from three to five grams.

Conclusion

After reading this article, we can conclude that potassium is an extremely important chemical element. It is necessary for the synthesis of many compounds in the chemical industry. In addition, it is used in many other industries. It is also very important for the human body, so it must be regularly and in the required amount to go there with food.