Analysis of potassium according to the chemistry plan. Phosphorus and its compounds. Practical application of phosphorus compounds

Part I

According to the plan discussed in the last lesson, characterize the element phosphorus.
1) This is a member of the VA group PS, 3rd small period.
2) The electronic formula of the atom:+15R 2e, 6e, 5e.
3) Phosphorus can exhibit oxidizing properties with respect to metals and hydrogen, as well as reducing properties with respect to more electronegative elements, for example: O, Cl.
4-6) Phosphorus is characterized by the phenomenon of allotropy. It forms two allotropic modifications: R red and R white. The first has an atomic crystal lattice, and the second has a molecular crystal lattice and the formula P4. Therefore, the reason for the allotropy of phosphorus is the crystal lattice, i.e. different structure.
Phosphorus red and P4 molecules are formed due to the covalent non-polar bond. Between P4 molecules are weak intermolecular forces of interaction.
7-8) P > active HM than Si, but< активный, чем S.
Phosphorus< активный восстановитель, чем Si, но >active than S.
9) Higher phosphorus oxide has the formula P2O5 and the name phosphorus oxide V. It is an acidic oxide.
It interacts (write down the equations possible reactions, including in full and abbreviated ionic form for reactions involving electrolytes):

10) The highest phosphorus hydroxide is phosphoric acid, the formula of which is.
It is a dibasic, oxygen-containing, water-soluble, non-volatile, stable but weak acid. Therefore, in the ionic equations of reactions involving phosphoric acid its formula should be written in molecular form.
The reaction with metals for phosphoric acid is uncharacteristic. The remaining properties are typical for acids. It interacts (make equations of possible reactions - molecular, full and abbreviated ionic):

11) The volatile hydrogen compound of phosphorus has the formula PH 3. It is built by covalent chemical bonding. The scheme of its formation:

Part II

1. Cross out the "extra".
4) Be

2. Which of the following groups contains only non-metals?
1) VIIA

3. Eliminate the "extra" element from the point of view of the possibility of the formation of allotropic modifications.
2) nitrogen

4. What type of chemical bond can only take place between atoms of non-metals?
1) covalent polar
4) covalent non-polar

5. Volatile solution hydrogen compound chlorine in water is called hydrochloric or hydrochloric acid.
Give the characteristics of the acid:
by basicity - monobasic
according to the content of oxygen - anoxic
by solubility - soluble
strength - strong.
The compound exhibits all the typical properties of acids (write down the equations of possible reactions in molecular, full and abbreviated ionic forms):

7. Chlorine(VII) oxide exhibits all the typical properties acid oxides(confirm with the equations of the corresponding reactions in molecular, full and abbreviated ionic forms, where applicable):

8. Perchloric acid HClO4- a very strong acid, exhibits all the typical properties of acids. Confirm this conclusion with the equations of the corresponding reactions in molecular, full and abbreviated ionic forms.

A) Characteristics of phosphorus.
1. Phosphorus - an element of the fifth group and the third period, Z = 15,
Ar(P) = 31.
Accordingly, the phosphorus atom contains 15 protons in the nucleus,
16 neutrons and 15 electrons. The structure of its electron shell
can be shown using the following diagram:

Phosphorus atoms exhibit both oxidizing properties (accepting
three electrons missing to complete the external level, while obtaining an oxidation state of -3, for example, in compounds with less electronegative elements - metals, hydrogen, etc.) and reducing properties (give 3 or 5 electrons to more electronegative elements - oxygen , halogens, etc., while acquiring oxidation states +3 and +5.)
Phosphorus is a less powerful oxidizing agent than nitrogen, but stronger than arsenic, which is associated with an increase in the atomic radii from nitrogen to arsenic. For the same reason, the restorative properties, on the contrary, are enhanced.
2. Phosphorus is a simple substance, a typical non-metal. Phosphorus is characterized by the phenomenon of allotropy. For example, there are allotropic modifications of phosphorus, such as white, red and black phosphorus, which have different chemical and physical properties.
3. The non-metallic properties of phosphorus are less pronounced than those of nitrogen, but stronger than those of arsenic (adjacent elements in the group).
4. The non-metallic properties of phosphorus are more pronounced than those of
silicon, but weaker than that of sulfur (adjacent elements in the period).
5. The highest phosphorus oxide has the formula P 2 O 5 . It's an acid oxide.
It exhibits all the typical properties of acidic oxides. So, for example, when it interacts with water, phosphoric acid is obtained.
P 2 O 5 + 3H 2 O \u003d\u003e 2H 3 RO 4.
When interacting with basic oxides and bases, it
gives salt.
P 2 O 5 + 3MgO \u003d Mg 3 (PO 4) 2; P 2 O 5 + 6KOH \u003d 2K 3 RO 4 + 3H 2 O.
6. Higher phosphorus hydroxide - phosphoric acid H 3 PO 4, dis-
the solution of which exhibits all the typical properties of acids: interaction with bases and basic oxides:
H 3 PO 4 + 3NaOH \u003d Na 3 PO 4 + 3H 2 O. 2H 3 RO 4 + 3CaO \u003d Ca, (PO 4) 2 ↓ + 3H 2 O.
7. Phosphorus forms a volatile compound H 3 P - phosphine.

B) Characteristics of potassium.
1. Potassium has serial number 19, Z = 19 and relative atomic mass Ar(K) = 39. Accordingly, the charge of the nucleus of its atom is +19 ( is equal to the number protons). Therefore, the number of neutrons in the nucleus is 20. Since the atom is electrically neutral, the number of electrons contained in the potassium atom is also 19. The potassium element is in the fourth period of the periodic system, which means that all electrons are located on four energy levels. Thus, the structure of the potassium atom is written as follows:

Based on the structure of the atom, it is possible to predict the degree of oxidation
potassium in its compounds. Since in chemical reactions the potassium atom donates one outer electron, exhibiting reducing properties, therefore, it acquires an oxidation state of +1.
The reducing properties of potassium are more pronounced than those of
trium, but weaker than that of rubidium, which is associated with an increase in radii from Na to Rb.
2. Potassium is a simple substance, it is characterized by a metallic
crystal lattice and metal chemical bond, and hence all the properties typical of metals.
3. The metallic properties of potassium are more pronounced than those of
trium, but weaker than that of rubidium, tk. a potassium atom donates an electron more easily than a sodium atom, but harder than a rubidium atom.
4. The metallic properties of potassium are more pronounced than those of calcium, because one electron of a potassium atom is easier to remove than two electrons
calcium atom.
5. Potassium oxide K 2 O is a basic oxide and exhibits all the typical properties of basic oxides. Interaction with acids and acid oxides.
K 2 O + 2HCl \u003d 2KCl + H 2 O; K 2 O + SO 3 \u003d K 2 SO 4.
6. Potassium hydroxide corresponds to the base (alkali) KOH, which exhibits all the characteristic properties of bases: interaction with acids and acid oxides.
KOH + HNO 3 \u003d KNO 3 + H 2 O; 2KOH + N 2 O 5 \u003d 2KNO 3 + H 2 O.
7. Potassium does not form a volatile hydrogen compound, but forms potassium hydride KH.

Phosphorus should be given a special place among biogenic elements. Indeed, without it, the existence of such vital compounds as, for example, ATP or phospholipids, as well as many others, is impossible. At the same time, the inorganic matter of this element is very rich in various molecules. Phosphorus and its compounds are widely used in industry, are important participants in biological processes, and are used in various branches of human activity. Therefore, consider what this element is, what its simple substance and the most important compounds are.

Phosphorus: general characteristics of the element

Position in periodic system can be described in several paragraphs.

1. Fifth group, main subgroup.
2. Third minor period.
3. Ordinal number - 15.
4. Atomic mass - 30.974.
5. The electronic configuration of the atom is 1s 2 2s 2 2p 6 3s 2 3p 3 .
6. Possible oxidation states from -3 to +5.
7. Chemical symbol - Р, pronunciation in formulas "pe". The name of the element is phosphorus. Latin name Phosphorus.

The history of the discovery of this atom goes back to the distant XII century. Even in the records of alchemists there was information indicating the receipt of an unknown "luminous" substance. However, the official date for the synthesis and discovery of phosphorus was 1669. The bankrupt merchant Brand, in search of the philosopher's stone, accidentally synthesized a substance capable of emitting a glow and burning with a bright blinding flame. He did this by repeatedly calcining human urine.

After it, independently of each other, in approximately the same ways, this element was obtained:

• I. Kunkel;
• R. Boyle;
• A. Marggraf;
• K. Scheele;
• A. Lavoisier.

Today, one of the most popular methods for the synthesis of this substance is the reduction from the corresponding phosphorus-containing minerals at high temperatures under the influence of carbon monoxide and silica. The process is carried out in special furnaces. Phosphorus and its compounds are very important substances both for living beings and for many syntheses in the chemical industry. Therefore, one should consider what a given element is as a simple substance and where it is found in nature.

The simple substance phosphorus

It is difficult to name any particular compound when we are talking about phosphorus. This is due to the numerous allotropic modifications that this element has. There are four main varieties of the simple substance phosphorus.

1. White. This is a compound whose formula is P 4 . It is a white volatile substance with a sharp unpleasant odor of garlic. It ignites spontaneously in air at normal temperatures. Burns with a luminous pale green light. Very poisonous and life-threatening. The chemical activity is extremely high, so it is obtained and stored under a layer of purified water. This is possible due to poor solubility in polar solvents. White phosphorus is best suited for this carbon disulfide and organic matter. When heated, it is capable of transforming into the next allotropic form - red phosphorus. When condensing and cooling vapors, it is able to form layers. Oily to the touch, soft, easy to cut with a knife, white color(slightly yellowish). Melting point 44 0 C. Due to its chemical activity, it is used in syntheses. But because of the toxicity, it does not have a wide industrial application.
2. Yellow. This is a poorly refined form white phosphorus. It is even more poisonous, it also smells unpleasantly of garlic. Ignites and burns with a bright luminous green flame. These yellow or brown crystals do not dissolve at all in water; when completely oxidized, they emit puffs of white smoke with the composition P 4 O 10.
3. Red phosphorus and its compounds are the most common and most commonly used modification of this substance in industry. Pasty red mass, which high blood pressure can pass into the form of violet crystals, is chemically inactive. It is a polymer that can only dissolve in certain metals and nothing else. At a temperature of 250 0 C, it sublimates, turning into a white modification. Not as toxic as previous forms. However, long-term exposure to the body is toxic. It is used in the application of an incendiary coating on matchboxes. This is explained by the fact that it cannot ignite spontaneously, but it explodes (ignites) during denotation and friction.
4. The black. According to external data, it is very similar to graphite, it is also greasy to the touch. It's a semiconductor electric current. Dark crystals, shiny, which are not able to dissolve in any solvents at all. For it to ignite, it takes a lot high temperatures and preheating.

Also interesting not so long ago open form phosphorus - metallic. It is a conductor and has a cubic crystal lattice.

Chemical properties

The chemical properties of phosphorus depend on what form it is in. As mentioned above, the most active yellow and white modification. In general, phosphorus is able to interact with:

• metals, forming phosphides and acting as an oxidizing agent;
• non-metals, acting as a reducing agent and forming volatile and non-volatile compounds of various kinds;
• strong oxidizing agents, turning into;
• with concentrated caustic alkalis according to the type of disproportionation;
• with water at very high temperatures;
• with oxygen to form various oxides.

The chemical properties of phosphorus are similar to those of nitrogen. After all, he is part of the pnictogen group. However, the activity is several orders of magnitude higher due to the variety of allotropic modifications.

Being in nature

As a biogenic element, phosphorus is very common. Its percentage in the earth's crust is 0.09%. This is a fairly large indicator. Where is this atom found in nature? There are several main places:

• the green part of plants, their seeds and fruits;
• animal tissues (muscles, bones, tooth enamel, many important organic compounds);
• Earth's crust;
• the soil;
• rocks and minerals;
• sea ​​water.

In this case, we can only talk about connected forms, but not about simple matter. After all, he is extremely active, and this does not allow him to be free. Among the minerals, the richest in phosphorus are:

• English;
• fluorapaptite;
• svanbergite;
• phosphorite and others.

The biological significance of this element cannot be overestimated. After all, it is part of such compounds as:

• proteins;
• phospholipids;
• phosphoproteins;
• enzymes.

That is, all those that are vital and from which the whole organism is built as a whole. Daily rate for an average adult about 2 grams.

Phosphorus and its compounds

As a very active element, this element forms many different substances. After all, it also forms phosphides, and itself acts as a reducing agent. Due to this, it is difficult to name an element that would be inert when reacting with it. Therefore, the formulas of phosphorus compounds are extremely diverse. There are several classes of substances in the formation of which he is an active participant.

1. Binary compounds - oxides, phosphides, volatile hydrogen compound, sulfide, nitride and others. For example: P 2 O 5, PCL 3, P 2 S 3, PH 3 and others.
2. Complex substances: salts of all types (medium, acidic, basic, double, complex), acids. Example: H 3 RO 4, Na 3 PO 4, H 4 P 2 O 6, Ca (H 2 PO 4) 2, (NH 4) 2 HPO 4 and others.
3. Oxygen-containing organic compounds: proteins, phospholipids, ATP, DNA, RNA and others.

Most of the designated types of substances are of great industrial and biological importance. The use of phosphorus and its compounds is possible both for medical purposes and for the manufacture of quite ordinary household items.

Connections with metals

Binary compounds of phosphorus with metals and less electronegative non-metals are called phosphides. These are salt-like substances that are extremely unstable when exposed to various agents. Rapid decomposition (hydrolysis) causes even ordinary water.

In addition, under the action of non-concentrated acids, the decomposition of the substance into the corresponding products also occurs. For example, if we talk about the hydrolysis of calcium phosphide, then the products will be metal hydroxide and phosphine:

Ca 3 P 2 + 6H 2 O \u003d 3Ca (OH) 2 + 2PH 3

And subjecting the phosphide to decomposition under the action of a mineral acid, we get the corresponding salt and phosphine:

Ca 3 P 2 + 6HCL \u003d 3CaCL 2 + 2PH 3

In general, the value of the compounds under consideration lies precisely in the fact that as a result a hydrogen compound of phosphorus is formed, the properties of which will be considered below.

Volatile substances based on phosphorus

There are two main ones:

• white phosphorus;
• phosphine.

We have already mentioned the first one above and cited the characteristics. They said that it was thick white smoke, highly poisonous, unpleasantly smelling and self-igniting when normal conditions.

But what is phosphine? This is the most common and well-known volatile substance, which includes the element in question. It is binary, and the second participant is hydrogen. The formula of the hydrogen compound of phosphorus is PH 3, the name is phosphine.

The properties of this substance can be described as follows.

1. A volatile colorless gas.
2. Very poisonous.
3. It has the smell of rotten fish.
4. It does not interact with water and dissolves very poorly in it. Let's well dissolve in organic matter.
5. Under normal conditions, it is very chemically active.
6. Self-ignites in air.
7. It is formed during the decomposition of metal phosphides.

Another name is Phosphate. Stories from ancient times are associated with it. It's all about what people sometimes saw and see now in cemeteries, swamps. Spherical or candle-like lights that appear here and there, giving the impression of movement, were considered a bad omen and were very much feared. superstitious people. The reason for this phenomenon is modern views some scientists, can be considered spontaneous combustion of phosphine, which is formed naturally during the decomposition of organic residues, both plant and animal. The gas comes out and, in contact with oxygen in the air, ignites. Flame color and size may vary. Most often, these are greenish bright lights.

Obviously, all volatile phosphorus compounds are poisonous substances that are easy to detect by sharp bad smell. This sign helps to avoid poisoning and unpleasant consequences.

Compounds with non-metals

If phosphorus behaves as a reducing agent, then we should talk about binary compounds with non-metals. Most often, they are more electronegative. So, we can distinguish several types of substances of this kind:

• a compound of phosphorus and sulfur - phosphorus sulfide P 2 S 3;
• phosphorus chloride III, V;
• oxides and anhydride;
• bromide and iodide and others.

The chemistry of phosphorus and its compounds is diverse, so it is difficult to identify the most important of them. If we talk specifically about the substances that are formed from phosphorus and non-metals, then oxides and chlorides of various compositions are of the greatest importance. They are used in chemical syntheses as dewatering agents, as catalysts, and so on.

So, one of the most powerful drying agents is the highest - P 2 O 5. It attracts water so strongly that upon direct contact with it, a violent reaction occurs with strong noise accompaniment. By itself, the substance is a white snow-like mass, in terms of its state of aggregation, it is closer to an amorphous one.

It is known that organic chemistry by the number of compounds far exceeds the inorganic one. This is explained by the phenomenon of isomerism and the ability of carbon atoms to form chains of atoms of various structures, closing with each other. Naturally, there is a certain order, that is, a classification, to which all organic chemistry is subject. Connection classes are different, however, we are interested in one specific one, directly related to the element in question. These are oxygen-containing compounds with phosphorus. These include:

• coenzymes - NADP, ATP, FMN, pyridoxal phosphate and others;
• proteins;
• nucleic acids, since the phosphoric acid residue is part of the nucleotide;
• phospholipids and phosphoproteins;
• enzymes and catalysts.

The type of ion in which phosphorus is involved in the formation of a molecule of these compounds is the following - PO 4 3-, that is, it is an acid residue of phosphoric acid. It is present in some proteins as a free atom or a simple ion.

For the normal functioning of every living organism, this element and the organic compounds formed by it are extremely important and necessary. Indeed, without protein molecules, it is impossible to build a single structural part of the body. And DNA and RNA are the main carriers and transmitters hereditary information. In general, all connections must be present without fail.

The use of phosphorus in industry

The use of phosphorus and its compounds in industry can be characterized in several points.

1. Used in the manufacture of matches, explosive compounds, incendiary bombs, some fuels, lubricants.
2. As a gas absorber, as well as in the manufacture of incandescent lamps.
3. To protect metals from corrosion.
4. IN agriculture as soil fertilizer.
5. As a water softener.
6. In chemical syntheses in the production of various substances.

The role in living organisms is reduced to participation in the formation of tooth enamel and bones. Participation in the reactions of ana- and catabolism, as well as maintaining the buffering of the internal environment of the cell and biological fluids. It is the basis in the synthesis of DNA, RNA, phospholipids.