Ferrous sulfate 3 chemical formula. Iron and its compounds

17. d -elements. Iron, general characteristics, properties. Oxides and hydroxides, KO and OM, characteristic, biorol, ability to form complexation.

1. General characteristics.

Iron - d-element of the secondary subgroup of the eighth group of the fourth period of the PSCE with atomic number 26.

One of the most widespread metals in the earth's crust (second only to aluminum).

A simple substance iron is a malleable metal of a silvery-white color with a high chemical reactivity: iron quickly corrodes at high temperatures or high humidity in the air.

4Fe + 3O2 + 6H2O = 4Fe (OH) 3

In pure oxygen, iron burns, and in a finely dispersed state it ignites spontaneously in air.

3Fe + 2O2 = FeO + Fe2O3

3Fe + 4H2O = FeO * Fe2O3

FeO * Fe2O3 = Fe3O4 (iron scale)

Actually, iron is usually called its alloys with a low content of impurities (up to 0.8%), which retain the softness and ductility of pure metal. But in practice, alloys of iron with carbon are more often used: steel (up to 2.14 wt% carbon) and cast iron (more than 2.14 wt% carbon), as well as stainless (alloyed) steel with the addition of alloying metals (chromium, manganese, nickel, etc.). The set of specific properties of iron and its alloys make it "metal No. 1" in importance for humans.

In nature, iron is rarely found in its pure form, most often it is found in the composition of iron-nickel meteorites. The prevalence of iron in the earth's crust is 4.65% (4th place after O, Si, Al). It is also believed that iron makes up most of the earth's core.

2.Properties

1.Phys. Iron is a typical metal, in a free state it is silvery-white with a grayish tint. Pure metal is ductile, various impurities (in particular - carbon) increase its hardness and brittleness. Possesses pronounced magnetic properties. The so-called "iron triad" is often distinguished - a group of three metals (iron Fe, cobalt Co, nickel Ni), which have similar physical properties, atomic radii and electronegativity values.

2.Chem.sv-va.

Oxidation state	Oxide	Hydroxide	Character	Notes (edit)
			Weak basic
			Very weak base, sometimes amphoteric
	Not received	*	Acid	Strong oxidizing agent

Iron is characterized by the oxidation states of iron - +2 and +3.

The oxidation state +2 corresponds to black oxide FeO and green hydroxide Fe (OH) 2. They are basic. In salts, Fe (+2) is present as a cation. Fe (+2) is a weak reducing agent.

The oxidation state +3 corresponds to the red-brown oxide Fe 2 O 3 and the brown hydroxide Fe (OH) 3. They are amphoteric in nature, although acidic, and their basic properties are poorly expressed. So, Fe 3+ ions completely hydrolyzed even in an acidic environment. Fe (OH) 3 dissolves (and even then not completely), only in concentrated alkalis. Fe 2 O 3 reacts with alkalis only upon fusion, giving ferrites(formal acid salts of non-existing free acid HFeO 2):

Iron (+3) most often exhibits weak oxidizing properties.

The oxidation states +2 and +3 easily pass among themselves when the redox conditions change.

In addition, there is an oxide Fe 3 O 4, the formal oxidation state of iron in which is +8/3. However, this oxide can also be considered as iron (II) ferrite Fe +2 (Fe +3 O 2) 2.

There is also an oxidation state of +6. The corresponding oxide and hydroxide in free form does not exist, but salts - ferrates (for example, K 2 FeO 4) have been obtained. Iron (+6) is in them in the form of an anion. Ferrates are strong oxidizing agents.

Pure metallic iron is stable in water and dilute solutions alkalis... Iron does not dissolve in cold concentrated sulfuric and nitric acids due to the passivation of the metal surface with a strong oxide film. Hot concentrated sulfuric acid, being a stronger oxidizing agent, interacts with iron.

WITH saline and diluted (approximately 20%) sulfuric acids iron reacts to form iron (II) salts:

When iron reacts with approximately 70% sulfuric acid when heated, the reaction proceeds with the formation iron (III) sulfate:

3.Oxides and hydroxides, KO and OM har-ka ...

Iron (II) compounds

Iron oxide (II) FeO has basic properties, the base Fe (OH) 2 corresponds to it. Iron (II) salts are light green in color. When stored, especially in humid air, they turn brown due to oxidation to iron (III). The same process occurs during storage of aqueous solutions of iron (II) salts:

Of iron (II) salts in aqueous solutions, stable Mohr's salt- double sulfate of ammonium and iron (II) (NH 4) 2 Fe (SO 4) 2 6H 2 O.

A reagent for Fe 2+ ions in solution can be potassium hexacyanoferrate (III) K 3 (red blood salt). When Fe 2+ and 3− ions interact, a precipitate forms turnboolean blue:

For the quantitative determination of iron (II) in solution, use phenanthroline forming a red FePhen 3 complex with iron (II) in a wide pH range (4-9)

Iron (III) compounds

Iron oxide (III) Fe 2 O 3 weak amphoterine, it is answered by an even weaker base than Fe (OH) 2, Fe (OH) 3, which reacts with acids:

Fe 3+ salts are prone to the formation of crystalline hydrates. In them, the Fe 3+ ion is usually surrounded by six water molecules. These salts are pink or purple in color. The Fe 3+ ion is completely hydrolyzed even in an acidic environment. At pH> 4, this ion is almost completely precipitated as Fe (OH) 3:

With the partial hydrolysis of the Fe 3+ ion, multinuclear oxo and hydroxocations are formed, which makes the solutions brown. The main properties of iron (III) hydroxide Fe (OH) 3 are very weak. It is capable of reacting only with concentrated alkali solutions:

The resulting iron (III) hydroxo complexes are stable only in strongly alkaline solutions. When solutions are diluted with water, they are destroyed, and Fe (OH) 3 precipitates.

When alloyed with alkalis and oxides of other metals, Fe 2 O 3 forms a variety of ferrites:

Iron (III) compounds in solutions are reduced by metallic iron:

Iron (III) is capable of forming double sulfates with singly charged cations type alum, for example, KFe (SO 4) 2 - potassium iron alum, (NH 4) Fe (SO 4) 2 - ammonium iron alum, etc.

For the qualitative detection of iron (III) compounds in solution, the qualitative reaction of Fe 3+ ions with thiocyanate ions is used SCN − ... When Fe 3+ ions interact with SCN - anions, a mixture of bright red thiocyanate complexes of iron 2+, +, Fe (SCN) 3, - is formed. The composition of the mixture (and hence the intensity of its color) depends on various factors; therefore, this method is inapplicable for an accurate qualitative determination of iron.

Another high-quality reagent for Fe 3+ ions is potassium hexacyanoferrate (II) K 4 (yellow blood salt). The interaction of Fe 3+ and 4− ions produces a bright blue precipitate Prussian blue:

Iron (VI) compounds

Ferrata- salt of non-existing free iron acid H 2 FeO 4. These are violet-colored compounds, resembling permanganates in oxidizing properties, and sulfates in solubility. Ferrates are obtained by the action of gaseous chlorine or ozone on a suspension of Fe (OH) 3 in alkali , for example, potassium ferrate (VI) K 2 FeO 4. The ferrates are purple.

Ferrata can also be obtained electrolysis 30% alkali solution on an iron anode:

Ferrates are strong oxidants. In an acidic environment, they decompose with the release of oxygen:

The oxidizing properties of ferrates are used for disinfection of water.

4 biorol

1) In living organisms, iron is an important trace element that catalyzes the processes of oxygen exchange (respiration).

2) Usually iron is included in enzymes in the form of a complex. In particular, this complex is present in hemoglobin - the most important protein that provides oxygen transport with blood to all organs of humans and animals. And it is he who stains the blood in a characteristic red color.

4) An excess dose of iron (200 mg or more) can have toxic effects. An overdose of iron inhibits the antioxidant system of the body, therefore, it is not recommended to use iron supplements for healthy people.

Designation - Fe (Iron);
Period - IV;
Group - 8 (VIII);
Atomic mass - 55.845;
Atomic number - 26;
Atom radius = 126 pm;
Covalent radius = 117 pm;
Distribution of electrons - 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2;
melting point = 1535 ° C;
boiling point = 2750 ° C;
Electronegativity (Pauling / Alpred and Rohov) = 1.83 / 1.64;
Oxidation state: +8, +6, +4, +3, +2, +1, 0;
Density (n. At.) = 7.874 g / cm 3;
Molar volume = 7.1 cm 3 / mol.

Iron compounds:

Iron is the most abundant metal in the earth's crust (5.1% by mass) after aluminum.

On Earth, iron in a free state is found in small quantities in the form of nuggets, as well as in fallen meteorites.

Iron is mined industrially at iron ore deposits, from iron-containing minerals: magnetic, red, brown iron ore.

It should be said that iron is a part of many natural minerals, causing their natural color. The color of minerals depends on the concentration and ratio of iron ions Fe 2+ / Fe 3+, as well as on the atoms surrounding these ions. For example, the presence of impurities of iron ions affects the color of many precious and semiprecious stones: topaz (from pale yellow to red), sapphires (from blue to dark blue), aquamarines (from light blue to greenish blue), etc.

Iron is found in the tissues of animals and plants, for example, in the body of an adult there is about 5 g of iron. Iron is a vital element, it is part of the protein hemoglobin, participating in the transport of oxygen from the lungs to tissues and cells. With a lack of iron in the human body, anemia develops (iron deficiency anemia).

Rice. The structure of the iron atom.

The electronic configuration of the iron atom is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2 (see Electronic structure of atoms). In the formation of chemical bonds with other elements, 2 electrons can participate in the outer 4s-level + 6 electrons of the 3d-sublevel (a total of 8 electrons), therefore, in compounds, iron can take the oxidation states +8, +6, +4, +3, +2, +1, (the most common are +3, +2). Iron has an average chemical activity.

Rice. Iron oxidation states: +2, +3.

Physical properties of iron:

silver-white metal;
in its pure form, it is quite soft and plastic;
possesses good heat and electrical conductivity.

Iron exists in the form of four modifications (differ in the structure of the crystal lattice): α-iron; β-iron; γ-iron; δ-iron.

Iron chemical properties

reacts with oxygen, depending on the temperature and oxygen concentration, various products or a mixture of iron oxidation products (FeO, Fe 2 O 3, Fe 3 O 4) can be formed:
3Fe + 2O 2 = Fe 3 O 4;
iron oxidation at low temperatures:
4Fe + 3O 2 = 2Fe 2 O 3;
reacts with water vapor:
3Fe + 4H 2 O = Fe 3 O 4 + 4H 2;
finely crushed iron reacts when heated with sulfur and chlorine (ferrous sulfide and chloride):
Fe + S = FeS; 2Fe + 3Cl 2 = 2FeCl 3;
at high temperatures reacts with silicon, carbon, phosphorus:
3Fe + C = Fe 3 C;
with other metals and with non-metals, iron can form alloys;
iron displaces less active metals from their salts:
Fe + CuCl 2 = FeCl 2 + Cu;
with dilute acids, iron acts as a reducing agent, forming salts:
Fe + 2HCl = FeCl 2 + H 2;
with dilute nitric acid, iron forms various acid reduction products, depending on its concentration (N 2, N 2 O, NO 2).

Getting and using iron

Industrial iron is obtained smelting cast iron and steel.

Cast iron is an alloy of iron with admixtures of silicon, manganese, sulfur, phosphorus, carbon. The carbon content in cast iron exceeds 2% (in steel less than 2%).

Pure iron is obtained:

in oxygen converters made of cast iron;
reduction of iron oxides with hydrogen and bivalent carbon monoxide;
electrolysis of the corresponding salts.

Pig iron is obtained from iron ores by reduction of iron oxides. Pig iron is smelted in blast furnaces. The blast furnace uses coke as a heat source.

A blast furnace is a very complex technical structure with a height of several tens of meters. It is lined with refractory bricks and protected by an outer steel casing. As of 2013, the largest blast furnace was built in South Korea by the POSCO steel company at the Gwangyang steel plant (the furnace volume after modernization was 6,000 cubic meters with an annual capacity of 5,700,000 tons).

Rice. Blast furnace.

The process of smelting pig iron in a blast furnace goes on continuously for several decades until the furnace reaches its end of life.

Rice. The process of smelting pig iron in a blast furnace.

beneficiated ores (magnetic, red, brown iron ore) and coke are poured through the top, located at the very top of the blast furnace;
the processes of iron reduction from ore under the influence of carbon monoxide (II) occur in the middle part of a blast furnace (mine) at a temperature of 450-1100 ° C (iron oxides are reduced to metal):
- 450-500 ° C - 3Fe 2 O 3 + CO = 2Fe 3 O 4 + CO 2;
- 600 ° C - Fe 3 O 4 + CO = 3FeO + CO 2;
- 800 ° C - FeO + CO = Fe + CO 2;
- part of the bivalent iron oxide is reduced by coke: FeO + C = Fe + CO.
in parallel, there is a process of reduction of silicon and manganese oxides (included in iron ore in the form of impurities), silicon and manganese are part of the cast iron:
- SiO 2 + 2C = Si + 2CO;
- Mn 2 O 3 + 3C = 2Mn + 3CO.
during thermal decomposition of limestone (introduced into a blast furnace), calcium oxide is formed, which reacts with silicon and aluminum oxides contained in the ore:
- CaCO 3 = CaO + CO 2;
- CaO + SiO 2 = CaSiO 3;
- CaO + Al 2 O 3 = Ca (AlO 2) 2.
at 1100 ° C, the iron reduction process stops;
below the shaft is the steaming, the widest part of the blast furnace, below which follows a shoulder, in which the coke burns out and liquid products of smelting are formed - pig iron and slag, accumulating at the very bottom of the furnace - the hearth;
in the upper part of the hearth at a temperature of 1500 ° C in a stream of blown air, intensive combustion of coke occurs: C + O 2 = CO 2;
passing through the red-hot coke, carbon monoxide (IV) is converted into carbon monoxide (II), which is a reducing agent for iron (see above): CO 2 + C = 2CO;
slags formed by calcium silicates and aluminosilicates are located above the cast iron, protecting it from the action of oxygen;
through special holes located at different levels of the hearth, cast iron and slag are discharged outside;
Most of the pig iron goes for further processing - steel smelting.

Steel is smelted from cast iron and scrap metal by the converter method (open-hearth is already obsolete, although it is still used) or by electric melting (in electric furnaces, induction furnaces). The essence of the process (redistribution of cast iron) is to reduce the concentration of carbon and other impurities by oxidation with oxygen.

As mentioned above, the carbon concentration in steel does not exceed 2%. Due to this, steel, in contrast to cast iron, is quite easily forged and rolled, which makes it possible to manufacture various products from it with high hardness and strength.

The hardness of steel depends on the carbon content (the more carbon, the harder the steel) in a particular steel grade and heat treatment conditions. When tempered (slow cooling), the steel becomes soft; when quenched (quickly cooled), the steel is very hard.

To give the steel the desired specific properties, ligating additives are added to it: chromium, nickel, silicon, molybdenum, vanadium, manganese, etc.

Cast iron and steel are the most important structural materials in the overwhelming majority of sectors of the national economy.

The biological role of iron:

the body of an adult contains about 5 g of iron;
iron plays an important role in the work of the hematopoietic organs;
iron is a part of many complex protein complexes (hemoglobin, myoglobin, various enzymes).

The first items made of iron and its alloys were found during excavations and date back to about 4 millennium BC. That is, even the ancient Egyptians and Sumerians used meteorite deposits of this substance to make jewelry and household items, as well as weapons.

Today, iron compounds of various kinds, as well as pure metal, are the most common and used substances. It is not for nothing that the 20th century was considered iron. Indeed, before the emergence and widespread distribution of plastic and related materials, it was this compound that was of decisive importance for a person. What this element is and what substances it forms, we will consider in this article.

Iron chemical element

If we consider the structure of the atom, then first of all it is necessary to indicate its location in the periodic table.

The serial number is 26.
The period is the fourth big one.
Group eighth, subgroup side.
The atomic weight is 55.847.
The structure of the outer electron shell is denoted by the formula 3d 6 4s 2.
- Fe.
The name is iron, the reading in the formula is "ferrum".
In nature, there are four stable isotopes of the element under consideration with mass numbers 54, 56, 57, 58.

The chemical element iron also has about 20 different isotopes that are not very stable. Possible oxidation states that a given atom can exhibit:

Not only the element itself is important, but also its various compounds and alloys.

Physical properties

As a simple substance, iron has a pronounced metallicity. That is, it is a silvery-white metal with a gray tint with a high degree of malleability and ductility and a high melting and boiling point. If we consider the characteristics in more detail, then:

melting point - 1539 0 С;
boiling - 2862 0 С;
activity - medium;
refractoriness - high;
exhibits pronounced magnetic properties.

Depending on conditions and different temperatures, there are several modifications that iron forms. Their physical properties differ from the fact that the crystal lattices differ.

All modifications have different types of crystal lattice structures, and also differ in magnetic properties.

Chemical properties

As mentioned above, the simple substance iron exhibits an average chemical activity. However, in a finely dispersed state, it can spontaneously ignite in air, and in pure oxygen the metal itself burns out.

Corrosion ability is high, therefore, the alloys of this substance are covered with alloying compounds. Iron is able to interact with:

acids;
oxygen (including air);
gray;
halogens;
when heated - with nitrogen, phosphorus, carbon and silicon;
with salts of less active metals, reducing them to simple substances;
with live steam;
with iron salts in the oxidation state +3.

It is obvious that, exhibiting such activity, the metal is able to form various compounds, diverse and polar in properties. And so it happens. Iron and its compounds are extremely diverse and find application in various branches of science, technology, and human industrial activity.

Distribution in nature

Natural compounds of iron are quite common, because it is the second most common element on our planet after aluminum. At the same time, in its pure form, the metal is extremely rare, in the composition of meteorites, which indicates its large clusters in space. The bulk is contained in the composition of ores, rocks and minerals.

If we talk about the percentage of the element in question in nature, then the following figures can be cited.

The nuclei of the terrestrial planets - 90%.
In the earth's crust - 5%.
In the Earth's mantle - 12%.
In the earth's core - 86%.
In river water - 2 mg / l.
In the sea and ocean - 0.02 mg / l.

The most common iron compounds form the following minerals:

magnetite;
limonite or brown iron ore;
vivianite;
pyrrhotite;
pyrite;
siderite;
marcasite;
lellingite;
mispickel;
milanterite and others.

This is still a long list, because there are really a lot of them. In addition, various man-made alloys are widespread. These are also such iron compounds, without which it is difficult to imagine the modern life of people. These include two main types:

cast irons;
become.

Also, it is iron that is a valuable additive in many nickel alloys.

Iron (II) compounds

These include those in which the oxidation state of the forming element is +2. They are quite numerous, because they include:

oxide;
hydroxide;
binary connections;
complex salts;
complex compounds.

Formulas of chemical compounds in which iron exhibits the indicated oxidation state are individual for each class. Let's consider the most important and common ones.

Iron (II) oxide. Black powder, does not dissolve in water. The nature of the connection is basic. It is capable of rapidly oxidizing, however, it can also be easily reduced to a simple substance. It dissolves in acids, forming the corresponding salts. Formula - FeO.
Iron (II) hydroxide. It is a white amorphous precipitate. Formed by the reaction of salts with bases (alkalis). Shows weak basic properties, is able to quickly oxidize in air to iron compounds +3. Formula - Fe (OH) 2.
Salts of the element in the indicated oxidation state. They have, as a rule, a pale green color of the solution, they are well oxidized even in air, acquiring and passing into iron salts 3. They dissolve in water. Examples of compounds: FeCL 2, FeSO 4, Fe (NO 3) 2.
Several compounds are of practical importance among the indicated substances. First, (II). It is the main supplier of ions to the body of a person with anemia. When such an ailment is diagnosed in a patient, then he is prescribed complex drugs, which are based on the compound in question. This is how the iron deficiency in the body is replenished.
Secondly, that is, iron (II) sulfate, together with copper, is used to destroy pests in crops. The method has been proving its effectiveness for more than a dozen years, therefore it is very appreciated by gardeners and gardeners.
Mora's Salt
This is a compound that is a crystalline hydrate of ferrous and ammonium sulfate. Its formula is written as FeSO 4 * (NH 4) 2 SO 4 * 6H 2 O. One of the iron (II) compounds, which is widely used in practice. The main areas of human use are as follows.
1. Pharmaceuticals.
2. Scientific research and laboratory titrimetric analyzes (to determine the content of chromium, potassium permanganate, vanadium).
3. Medicine - as a food supplement in case of a lack of iron in the patient's body.
4. For impregnation of wooden products, as Mohr's salt protects against decay processes.
There are other areas in which this substance is used. It got its name in honor of the German chemist, who first discovered the manifested properties.
Substances with the oxidation state of iron (III)
The properties of iron compounds, in which it exhibits an oxidation state of +3, are somewhat different from those discussed above. So, the character of the corresponding oxide and hydroxide is no longer basic, but pronounced amphoteric. Let's give a description of the main substances.

Among the examples given, from a practical point of view, such crystalline hydrate as FeCL 3 * 6H 2 O, or iron (III) chloride hexahydrate, is of great importance. It is used in medicine to stop bleeding and replenish iron ions in the body in case of anemia.
Iron (III) sulfate is used for the purification of drinking water, as it behaves like a coagulant.
Iron (VI) compounds
The formulas for the chemical compounds of iron, where it exhibits a special oxidation state of +6, can be written as follows:
- K 2 FeO 4;
- Na 2 FeO 4;
- MgFeO 4 and others.
They all have a common name - ferrates - and have similar properties (strong reducing agents). They are also capable of disinfecting and have a bactericidal effect. This allows them to be used for the treatment of drinking water on an industrial scale.
Complex compounds
Special substances are very important in analytical chemistry and not only. Such, which are formed in aqueous solutions of salts. These are complex iron compounds. The most popular and well-studied ones are as follows.
1. Potassium hexacyanoferrate (II) K 4. Another name for the compound is yellow blood salt. It is used for the qualitative determination of the iron ion Fe 3+ in a solution. As a result of exposure, the solution acquires a beautiful bright blue color, since another complex is formed - Prussian blue KFe 3+. Since ancient times it has been used as
2. Potassium hexacyanoferrate (III) K 3. Another name is red blood salt. It is used as a high-quality reagent for the determination of the iron ion Fe 2+. The result is a blue precipitate called turnboolean blue. Also used as a fabric dye.
Iron in organic matter
Iron and its compounds, as we have already seen, are of great practical importance in human economic life. However, in addition to this, its biological role in the body is no less great, on the contrary.
There is one very important protein that this element is part of. This is hemoglobin. It is thanks to him that oxygen is transported and uniform and timely gas exchange is carried out. Therefore, the role of iron in a vital process - breathing - is simply enormous.
In total, the human body contains about 4 grams of iron, which must be constantly replenished from consumed food.

DEFINITION

Iron- an element of the eighth group of the fourth period of the periodic table of chemical elements of D.I.Mendeleev.

And the languid number is 26. The symbol is Fe (Latin “ferrum”). One of the most widespread metals in the earth's crust (second only to aluminum).

Physical properties of iron

Iron is a gray metal. In its pure form, it is quite soft, malleable and ductile. Electronic configuration of the external energy level - 3d 6 4s 2. In its compounds, iron exhibits oxidation states "+2" and "+3". The melting point of iron is 1539C. Iron forms two crystalline modifications: α- and γ-iron. The first of them has a cubic body-centered lattice, the second - a cubic face-centered lattice. α-Iron is thermodynamically stable in two temperature ranges: below 912 and from 1394C to the melting point. Between 912 and 1394C γ-iron is stable.

The mechanical properties of iron depend on its purity - the content of even very small amounts of other elements in it. Solid iron has the ability to dissolve many elements in itself.

Iron chemical properties

Iron rusts quickly in humid air; covered with a brown bloom of hydrated iron oxide, which, due to its looseness, does not protect iron from further oxidation. Iron corrodes intensely in water; with abundant access of oxygen, hydrated forms of iron (III) oxide are formed:

2Fe + 3 / 2O 2 + nH 2 O = Fe 2 O 3 × H 2 O.

With a lack of oxygen or with difficult access, a mixed oxide (II, III) Fe 3 O 4 is formed:

3Fe + 4H 2 O (v) ↔ Fe 3 O 4 + 4H 2.

Iron dissolves in hydrochloric acid of any concentration:

Fe + 2HCl = FeCl 2 + H 2.

Dissolution in dilute sulfuric acid occurs similarly:

Fe + H 2 SO 4 = FeSO 4 + H 2.

In concentrated solutions of sulfuric acid, iron is oxidized to iron (III):

2Fe + 6H 2 SO 4 = Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O.

However, in sulfuric acid, the concentration of which is close to 100%, iron becomes passive and practically no interaction occurs. In dilute and moderately concentrated solutions of nitric acid, iron dissolves:

Fe + 4HNO 3 = Fe (NO 3) 3 + NO + 2H 2 O.

At high concentrations of nitric acid, dissolution slows down and iron becomes passive.

Like other metals, iron reacts with simple substances. Iron interacts with halogens (regardless of the type of halogen) occur when heated. The interaction of iron with bromine occurs at an increased vapor pressure of the latter:

2Fe + 3Cl 2 = 2FeCl 3;

3Fe + 4I 2 = Fe 3 I 8.

The interaction of iron with sulfur (powder), nitrogen and phosphorus also occurs when heated:

6Fe + N 2 = 2Fe 3 N;

2Fe + P = Fe 2 P;

3Fe + P = Fe 3 P.

Iron is capable of reacting with non-metals such as carbon and silicon:

3Fe + C = Fe 3 C;

Among the reactions of the interaction of iron with complex substances, the following reactions play a special role - iron is able to reduce metals in the order of activity to the right of it from salt solutions (1), to reduce iron (III) compounds (2):

Fe + CuSO 4 = FeSO 4 + Cu (1);

Fe + 2FeCl 3 = 3FeCl 2 (2).

Iron, at elevated pressure, reacts with a non-salt-forming oxide - CO with the formation of substances of a complex composition - carbonyls - Fe (CO) 5, Fe 2 (CO) 9 and Fe 3 (CO) 12.

Iron, in the absence of impurities, is stable in water and in dilute solutions of alkalis.

Getting iron

The main method for producing iron is from iron ore (hematite, magnetite) or electrolysis of solutions of its salts (in this case, "pure" iron is obtained, that is, iron without impurities).

Examples of problem solving

EXAMPLE 1

Exercise

Iron scale Fe 3 O 4 weighing 10 g was first treated with 150 ml of a hydrochloric acid solution (density 1.1 g / ml) with a mass fraction of hydrogen chloride of 20%, and then an excess of iron was added to the resulting solution. Determine the composition of the solution (in% by weight).

Solution

Let us write down the reaction equations according to the condition of the problem:

8HCl + Fe 3 O 4 = FeCl 2 + 2FeCl 3 + 4H 2 O (1);

2FeCl 3 + Fe = 3FeCl 2 (2).

Knowing the density and volume of the hydrochloric acid solution, you can find its mass:

m sol (HCl) = V (HCl) × ρ (HCl);

m sol (HCl) = 150 × 1.1 = 165 g.

Let's calculate the mass of hydrogen chloride:

m (HCl) = m sol (HCl) x ω (HCl) / 100%;

m (HCl) = 165 × 20% / 100% = 33 g.

The molar mass (mass of one mol) of hydrochloric acid, calculated using the table of chemical elements of D.I. Mendeleev - 36.5 g / mol. Let's find the amount of hydrogen chloride substance:

v (HCl) = m (HCl) / M (HCl);

v (HCl) = 33 / 36.5 = 0.904 mol.

The molar mass (mass of one mol) of the scale, calculated using the table of chemical elements of D.I. Mendeleev - 232 g / mol. Let's find the amount of scale substance:

v (Fe 3 O 4) = 10/232 = 0.043 mol.

According to equation 1, v (HCl): v (Fe 3 O 4) = 1: 8, therefore, v (HCl) = 8 v (Fe 3 O 4) = 0.344 mol. Then, the amount of chlorine substance calculated by the equation (0.344 mol) will be less than that indicated in the condition of the problem (0.904 mol). Therefore, hydrochloric acid is in excess and another reaction will occur:

Fe + 2HCl = FeCl 2 + H 2 (3).

Let us determine the amount of the substance of iron chlorides formed as a result of the first reaction (we denote a specific reaction with indices):

v 1 (FeCl 2): v (Fe 2 O 3) = 1: 1 = 0.043 mol;

v 1 (FeCl 3): v (Fe 2 O 3) = 2: 1;

v 1 (FeCl 3) = 2 × v (Fe 2 O 3) = 0.086 mol.

Let us determine the amount of hydrogen chloride that did not react in reaction 1 and the amount of iron (II) chloride substance formed during reaction 3:

v rem (HCl) = v (HCl) - v 1 (HCl) = 0.904 - 0.344 = 0.56 mol;

v 3 (FeCl 2): v rem (HCl) = 1: 2;

v 3 (FeCl 2) = 1/2 × v rem (HCl) = 0.28 mol.

Let us determine the amount of the FeCl 2 substance formed during reaction 2, the total amount of the FeCl 2 substance and its mass:

v 2 (FeCl 3) = v 1 (FeCl 3) = 0.086 mol;

v 2 (FeCl 2): v 2 (FeCl 3) = 3: 2;

v 2 (FeCl 2) = 3/2 × v 2 (FeCl 3) = 0.129 mol;

v sum (FeCl 2) = v 1 (FeCl 2) + v 2 (FeCl 2) + v 3 (FeCl 2) = 0.043 + 0.129 + 0.28 = 0.452 mol;

m (FeCl 2) = v sum (FeCl 2) × M (FeCl 2) = 0.452 × 127 = 57.404 g.

Let us determine the amount of substance and the mass of iron that has entered into reactions 2 and 3:

v 2 (Fe): v 2 (FeCl 3) = 1: 2;

v 2 (Fe) = 1/2 × v 2 (FeCl 3) = 0.043 mol;

v 3 (Fe): v rem (HCl) = 1: 2;

v 3 (Fe) = 1/2 × v rem (HCl) = 0.28 mol;

v sum (Fe) = v 2 (Fe) + v 3 (Fe) = 0.043 + 0.28 = 0.323 mol;

m (Fe) = v sum (Fe) × M (Fe) = 0.323 × 56 = 18.088 g.

Let us calculate the amount of substance and the mass of hydrogen released in reaction 3:

v (H 2) = 1/2 × v rem (HCl) = 0.28 mol;

m (H 2) = v (H 2) × M (H 2) = 0.28 × 2 = 0.56 g.

Determine the mass of the resulting solution m 'sol and the mass fraction of FeCl 2 in it:

m 'sol = m sol (HCl) + m (Fe 3 O 4) + m (Fe) - m (H 2);

Iron (II) sulfate, iron (III) sulfate.

Chemical properties

Ferrous sulfate is an inorganic compound, the salt formed sulfuric acid and iron. The substance is odorless, not volatile. The anhydrous form is in the form of colorless, opaque, small hygrocopy crystals. Crystalline hydrates have a characteristic greenish-blue color, tetrahydrates are green. Chemical formula of Iron Sulfate 2: FeSO4, racemic: O4SFe... The compound tastes astringent, with a metallic taste. The product is highly soluble in water. Molecular weight = 151.9 grams per mole.

The substance is released from ferrous sulfate ... Solution sulfate Fe (2) under the influence of oxygen, it is oxidized into iron sulfate 3. Decomposes at temperatures above 480 degrees Celsius into oxides.

Iron Sulfate 2 can be obtained by exposure to dilute sulfuric acid for scrap iron; as a by-product of the etching reaction of iron sheets, during descaling, during oxidative firing of pyrite.

The hydrolysis of Iron Sulfate 2 proceeds as a cation in an acidic medium. The first stage of hydrolysis: Fe2 + + SO42- + HOH ↔ FeOH + + SO42- + H +; theoretically, the second stage of hydrolysis can also occur: FeOH + + SO42- + HOH ↔ Fe (OH) 2 ↓ + SO42- + H +.

The substance is used:

for dyeing products and woolen fabric in black, in the production of ink, in the preservation of wood;
in chemical dosimetry, for the treatment of garden trees in agriculture;
in medicine during treatment iron deficiency anemia .

Iron sulfate 3 or iron tetrasulfide 6 3 Are light yellow paramagnetic fine crystals. The substance dissolves well in water, slowly - in ethyl alcohol. Chemical formula of Iron Sulfate 3: Fe2 (SO4) 3, racemic: Fe2O12S3... The substance has the ability to crystallize in the form of crystalline hydrates Fe2 (SO4) 3 n H2O... What matters most is iron (III) sulfate nonahydrate ... Aqueous solutions acquire a red-brown color due to the hydrolysis reaction proceeding along the cation. The compound decomposes when exposed to hot water and high temperatures. At 98 degrees nonahydrate turns into tetrahydrate , at temperatures above 125 degrees - in monohydrate and above 175 - in anhydrous Fe sulfate , which decomposes into oxides of sulfur and iron at temperatures over 600 degrees.

The substance is used:

in the processing of copper ore, for the treatment of waste water, industrial and municipal wastewater;
when dyeing fabrics and tanning in the leather industry;
as a flotation regulator, as a catalyst for certain reactions or as an oxidizing agent;
in medicine as a hemostatic agent.

pharmachologic effect

Antianemic, eliminating iron deficiency. Hemostatic (Iron Sulfate 3).

Pharmacodynamics and pharmacokinetics

Iron is the main trace element in the composition, myoglobin and other blood components. The substance takes part in redox reactions, binds and transfers oxygen molecules throughout the body, stimulates hematopoiesis and erythropoiesis ... Iron sulfate provides the synthesis of all iron-containing metabolites. After admission Fe with food, it is absorbed in the duodenum and transferred to the tissue depot with the help of enzymes transfersetins .

After taking the medicine inside, its active components are completely absorbed by the body. The maximum concentration in the blood is observed after 2-4 hours.

Indications for use

The tool is used:

for treatment and prevention iron deficiency anemia in children and adults;
in case of impaired absorption of iron from the digestive tract;
in patients with an increased need for iron, during breastfeeding, during intensive growth, with an unbalanced diet;
with chronic, accompanied by secretory insufficiency;
at some stages of treatment B12 deficiency anemia ;
with exacerbation;
during rehabilitation after gastric resection ;
for the treatment of premature babies;
for stimulation during infectious diseases and during;
when treating patients with achlorhydria , chronic, Crohn's disease , syndrome malabsorption .

Contraindications

Iron sulfate 2 is contraindicated for taking:

at the means;
in patients with metabolic disorders in the body, with hemosiderosis , hemochromatosis ;
patients with gastrointestinal dysfunction, which interferes with the absorption of iron;
with aplastic and hemolytic anemia ;
patients with thalassemia .

Side effects

Adverse reactions during treatment with Ferrous Sulfate are not common.

May appear:

, headache general weakness and irritability, epileptic syndrome and ;
feeling of pressure in the chest, or, nausea;
toothache, pain in the epigastric region;
skin rashes, itching, sore throat;
rarely - anaphylactic reactions .

Instructions for use (Method and dosage)

The medicine is prescribed by mouth. The minimum effective dosage in terms of elemental iron is 100 mg. The maximum amount of medicine that can be taken is up to 400 mg.

For prophylactic purposes, appoint from 30 to 60 mg of elemental iron per day.

Overdose

In case of an overdose, adverse reactions from taking the medication increase. There are: diarrhea , nausea, painful sensations in the abdomen, vomiting, and an increase in heart rate, increased capillary permeability, possible cardiovascular collapse ... As a therapy, the stomach is washed, injected deferoxamine for binding iron ions.

Interaction

When combined with, the absorption of iron preparations improves.

Combined intake of sulfate and antacids with magnesium, aluminum, calcium, penicillamine and cholestyramine slows down the absorption of iron.

When a drug is combined with corticosteroids, it mutually amplifies erythropoiesis .