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How Iron Oxide Is Formed 2. Inorganic Chemistry Cheat Sheet




The human body contains about 5 g of iron, most of it (70%) is part of the hemoglobin in the blood.

Physical Properties

In the free state, iron is a silvery-white metal with a grayish tinge. Pure iron is ductile and has ferromagnetic properties. In practice, iron alloys are commonly used - cast irons and steels.


Fe is the most important and most common element of the nine d-metals of the secondary subgroup of group VIII. Together with cobalt and nickel, it forms the "iron family".


When forming compounds with other elements, it often uses 2 or 3 electrons (B \u003d II, III).


Iron, like almost all d-elements of group VIII, does not show a higher valency equal to the group number. Its maximum valency reaches VI and is extremely rare.


The most typical compounds are those in which the Fe atoms are in the +2 and +3 oxidation states.


Methods for obtaining iron

1. Commercial iron (in an alloy with carbon and other impurities) is obtained by carbothermal reduction of its natural compounds according to the scheme:




Recovery occurs gradually, in 3 stages:


1) 3Fe 2 O 3 + CO = 2Fe 3 O 4 + CO 2


2) Fe 3 O 4 + CO = 3FeO + CO 2


3) FeO + CO \u003d Fe + CO 2


The cast iron resulting from this process contains more than 2% carbon. In the future, steels are obtained from cast iron - iron alloys containing less than 1.5% carbon.


2. Very pure iron is obtained in one of the following ways:


a) decomposition of pentacarbonyl Fe


Fe(CO) 5 = Fe + 5CO


b) hydrogen reduction of pure FeO


FeO + H 2 \u003d Fe + H 2 O


c) electrolysis of aqueous solutions of Fe +2 salts


FeC 2 O 4 \u003d Fe + 2СO 2

iron(II) oxalate

Chemical properties

Fe - a metal of medium activity, exhibits general properties characteristic of metals.


A unique feature is the ability to "rust" in humid air:



In the absence of moisture with dry air, iron begins to noticeably react only at T > 150°C; when calcined, “iron scale” Fe 3 O 4 is formed:


3Fe + 2O 2 = Fe 3 O 4


Iron does not dissolve in water in the absence of oxygen. At very high temperatures, Fe reacts with water vapor, displacing hydrogen from water molecules:


3 Fe + 4H 2 O (g) \u003d 4H 2


The rusting process in its mechanism is electrochemical corrosion. The rust product is presented in a simplified form. In fact, a loose layer of a mixture of oxides and hydroxides of variable composition is formed. Unlike the Al 2 O 3 film, this layer does not protect the iron from further destruction.

Types of corrosion


Corrosion protection of iron


1. Interaction with halogens and sulfur at high temperature.

2Fe + 3Cl 2 = 2FeCl 3


2Fe + 3F 2 = 2FeF 3



Fe + I 2 \u003d FeI 2



Compounds are formed in which the ionic type of bond predominates.

2. Interaction with phosphorus, carbon, silicon (iron does not directly combine with N 2 and H 2, but dissolves them).

Fe + P = Fe x P y


Fe + C = Fe x C y


Fe + Si = FexSiy


Substances of variable composition are formed, since berthollides (the covalent nature of the bond prevails in the compounds)

3. Interaction with "non-oxidizing" acids (HCl, H 2 SO 4 dil.)

Fe 0 + 2H + → Fe 2+ + H 2


Since Fe is located in the activity series to the left of hydrogen (E ° Fe / Fe 2+ \u003d -0.44V), it is able to displace H 2 from ordinary acids.


Fe + 2HCl \u003d FeCl 2 + H 2


Fe + H 2 SO 4 \u003d FeSO 4 + H 2

4. Interaction with "oxidizing" acids (HNO 3 , H 2 SO 4 conc.)

Fe 0 - 3e - → Fe 3+


Concentrated HNO 3 and H 2 SO 4 "passivate" iron, so at ordinary temperatures the metal does not dissolve in them. With strong heating, slow dissolution occurs (without release of H 2).


In razb. HNO 3 iron dissolves, goes into solution in the form of Fe 3+ cations, and the acid anion is reduced to NO *:


Fe + 4HNO 3 \u003d Fe (NO 3) 3 + NO + 2H 2 O


It dissolves very well in a mixture of HCl and HNO 3

5. Attitude to alkalis

Fe does not dissolve in aqueous solutions of alkalis. It reacts with molten alkalis only at very high temperatures.

6. Interaction with salts of less active metals

Fe + CuSO 4 \u003d FeSO 4 + Cu


Fe 0 + Cu 2+ = Fe 2+ + Cu 0

7. Interaction with gaseous carbon monoxide (t = 200°C, P)

Fe (powder) + 5CO (g) \u003d Fe 0 (CO) 5 iron pentacarbonyl

Fe(III) compounds

Fe 2 O 3 - iron oxide (III).

Red-brown powder, n. R. in H 2 O. In nature - "red iron ore".

Ways to get:

1) decomposition of iron hydroxide (III)


2Fe(OH) 3 = Fe 2 O 3 + 3H 2 O


2) pyrite roasting


4FeS 2 + 11O 2 \u003d 8SO 2 + 2Fe 2 O 3


3) decomposition of nitrate


Chemical properties

Fe 2 O 3 is a basic oxide with signs of amphoterism.


I. The main properties are manifested in the ability to react with acids:


Fe 2 O 3 + 6H + = 2Fe 3+ + ZN 2 O


Fe 2 O 3 + 6HCI \u003d 2FeCI 3 + 3H 2 O


Fe 2 O 3 + 6HNO 3 \u003d 2Fe (NO 3) 3 + 3H 2 O


II. Weak acid properties. Fe 2 O 3 does not dissolve in aqueous solutions of alkalis, but when fused with solid oxides, alkalis and carbonates, ferrites are formed:


Fe 2 O 3 + CaO \u003d Ca (FeO 2) 2


Fe 2 O 3 + 2NaOH \u003d 2NaFeO 2 + H 2 O


Fe 2 O 3 + MgCO 3 \u003d Mg (FeO 2) 2 + CO 2


III. Fe 2 O 3 - feedstock for iron production in metallurgy:


Fe 2 O 3 + ZS \u003d 2Fe + ZSO or Fe 2 O 3 + ZSO \u003d 2Fe + ZSO 2

Fe (OH) 3 - iron (III) hydroxide

Ways to get:

Obtained by the action of alkalis on soluble salts Fe 3+:


FeCl 3 + 3NaOH \u003d Fe (OH) 3 + 3NaCl


At the time of receipt of Fe(OH) 3 - red-brown mucosamorphous precipitate.


Fe (III) hydroxide is also formed during the oxidation of Fe and Fe (OH) 2 in humid air:


4Fe + 6H 2 O + 3O 2 \u003d 4Fe (OH) 3


4Fe(OH) 2 + 2Н 2 O + O 2 = 4Fe(OH) 3


Fe(III) hydroxide is the end product of hydrolysis of Fe 3+ salts.

Chemical properties

Fe(OH) 3 is a very weak base (much weaker than Fe(OH) 2). Shows noticeable acidic properties. Thus, Fe (OH) 3 has an amphoteric character:


1) reactions with acids proceed easily:



2) a fresh precipitate of Fe(OH) 3 is dissolved in hot conc. solutions of KOH or NaOH with the formation of hydroxo complexes:


Fe (OH) 3 + 3KOH \u003d K 3


In an alkaline solution, Fe (OH) 3 can be oxidized to ferrates (salts of iron acid H 2 FeO 4 not isolated in the free state):


2Fe(OH) 3 + 10KOH + 3Br 2 = 2K 2 FeO 4 + 6KBr + 8H 2 O

Fe 3+ salts

The most practically important are: Fe 2 (SO 4) 3, FeCl 3, Fe (NO 3) 3, Fe (SCN) 3, K 3 4 - yellow blood salt \u003d Fe 4 3 Prussian blue (dark blue precipitate)


b) Fe 3+ + 3SCN - \u003d Fe (SCN) 3 Fe (III) thiocyanate (blood red solution)

DEFINITION

Iron(II) oxide under normal conditions, it is a black powder (Fig. 1), decomposing upon moderate heating and re-forming from the decomposition products upon further heating.

After calcination, it is chemically inactive. Pyrophorene powder. Does not react with cold water. Shows amphoteric properties (with a predominance of basic). Easily oxidized by oxygen. It is reduced by hydrogen and carbon.

Rice. 1. Iron oxide (II). Appearance.

Chemical formula of iron oxide 2

The chemical formula of iron(II) oxide is FeO. The chemical formula shows the qualitative and quantitative composition of the molecule (how many and which atoms are present in it). According to the chemical formula, you can calculate the molecular weight of a substance (Ar (Fe) \u003d 56 amu, Ar (O) \u003d 16 amu):

Mr(FeO) = Ar(Fe) + Ar(O);

Mr(FeO) = 56 + 16 = 72.

Structural (graphical) formula of iron oxide 2

The structural (graphic) formula of a substance is more visual. It shows how atoms are connected to each other within a molecule. Below is the graphic formula of iron oxide (II):

Examples of problem solving

EXAMPLE 1

Exercise When neutralizing 25.5 g of saturated monobasic acid with an excess of sodium bicarbonate solution, 5.6 l (N.O.) of gas was released. Determine the molecular formula of the acid.
Solution We write the equation for the neutralization reaction of a saturated monobasic acid with an excess of sodium bicarbonate solution in general form:

C n H 2n+1 COOH + NaHCO 3 → C n H 2n+1 COONa + CO 2 + H 2 O.

Calculate the amount of carbon dioxide released during the reaction:

n(CO 2) \u003d V (CO 2) / V m;

n(CO 2) \u003d 5.6 / 22.4 \u003d 0.25 mol.

According to the reaction equation n(CO 2): n(C n H 2n+1 COOH) = 1:1, i.e. n (C n H 2n + 1 COOH) \u003d n (CO 2) \u003d 0.25 mol.

Calculate the molar mass of the limiting monobasic acid:

M(C n H 2n+1 COOH) = m(C n H 2n+1 COOH) / n(C n H 2n+1 COOH);

M(C n H 2 n +1 COOH) \u003d 25.5 / 0.25 \u003d 102 g / mol.

Let's determine the number of carbon atoms in the molecule of the limiting monobasic acid (the values ​​​​of relative atomic masses taken from the Periodic Table of D.I. Mendeleev are rounded up to integers: 12 for carbon, 1 for hydrogen and 16 for oxygen):

M(C n H 2n+1 COOH) = 12n + 2n + 1 + 12 + 16 + 16 +1 = 14n + 46;

14n + 46 = 102 g/mol;

So the molecular formula of the limiting monobasic acid is C 4 H 9 COOH.
Answer C4H9COOH

EXAMPLE 2

Exercise Set the molecular formula of an alkene if it is known that 2.8 g of it can add 1120 ml (N.O.) of hydrogen chloride.
Solution Let us write the equation for the reaction of the addition of hydrogen chloride to an alkene in general form:

C n H 2 n + HCl → C n H 2 n +1 Cl.

Calculate the amount of hydrogen chloride substance:

n(HCl) = V(HCl) / V m ;

n(HCl) = 1.2 / 22.4 = 0.05 mol.

According to the reaction equation n(HCl): n(C n H 2n) = 1:1, i.e. n (C n H 2n) \u003d n (HCl) \u003d 0.05 mol.

Calculate the molar mass of an alkene:

M(C n H 2n) = m(C n H 2n) / n(C n H 2n);

M(C n H 2 n) \u003d 2.8 / 0.05 \u003d 56 g / mol.

Let's determine the number of carbon atoms in an alkene molecule (the values ​​​​of relative atomic masses taken from the Periodic Table of D.I. Mendeleev are rounded up to integers: 12 for carbon and 1 for hydrogen):

M(C n H 2 n) = 12n + 2n = 14n;

14n= 56 g/mol;

So the molecular formula of the alkene is C 4 H 8.
Answer C 4 H 8

Iron is an element of a side subgroup of the eighth group of the fourth period of the periodic system of chemical elements of D. I. Mendeleev with atomic number 26. It is designated by the symbol Fe (lat. Ferrum). One of the most common metals in the earth's crust (second place after aluminum). Medium activity metal, reducing agent.

Main oxidation states - +2, +3

A simple substance iron is a malleable silver-white metal with a high chemical reactivity: iron quickly corrodes at high temperatures or high humidity in the air. In pure oxygen, iron burns, and in a finely dispersed state, it ignites spontaneously in air.

Chemical properties of a simple substance - iron:

Rusting and burning in oxygen

1) In air, iron is easily oxidized in the presence of moisture (rusting):

4Fe + 3O 2 + 6H 2 O → 4Fe(OH) 3

A heated iron wire burns in oxygen, forming scale - iron oxide (II, III):

3Fe + 2O 2 → Fe 3 O 4

3Fe + 2O 2 → (Fe II Fe 2 III) O 4 (160 ° С)

2) At high temperatures (700–900°C), iron reacts with water vapor:

3Fe + 4H 2 O - t ° → Fe 3 O 4 + 4H 2

3) Iron reacts with non-metals when heated:

2Fe+3Cl 2 →2FeCl 3 (200 °C)

Fe + S – t° → FeS (600 °С)

Fe + 2S → Fe +2 (S 2 -1) (700 ° С)

4) In a series of voltages, it is to the left of hydrogen, reacts with dilute acids Hcl and H 2 SO 4, while iron (II) salts are formed and hydrogen is released:

Fe + 2HCl → FeCl 2 + H 2 (reactions are carried out without air access, otherwise Fe +2 is gradually converted by oxygen into Fe +3)

Fe + H 2 SO 4 (diff.) → FeSO 4 + H 2

In concentrated oxidizing acids, iron dissolves only when heated, it immediately passes into the Fe 3+ cation:

2Fe + 6H 2 SO 4 (conc.) – t° → Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O

Fe + 6HNO 3 (conc.) – t° → Fe(NO 3) 3 + 3NO 2 + 3H 2 O

(in the cold, concentrated nitric and sulfuric acids passivate

An iron nail immersed in a bluish solution of copper sulphate is gradually covered with a coating of red metallic copper.

5) Iron displaces metals to the right of it in solutions of their salts.

Fe + CuSO 4 → FeSO 4 + Cu

Amphotericity of iron is manifested only in concentrated alkalis during boiling:

Fe + 2NaOH (50%) + 2H 2 O \u003d Na 2 ↓ + H 2

and a precipitate of sodium tetrahydroxoferrate(II) is formed.

Technical iron- alloys of iron with carbon: cast iron contains 2.06-6.67% C, steel 0.02-2.06% C, other natural impurities (S, P, Si) and artificially introduced special additives (Mn, Ni, Cr) are often present, which gives iron alloys technically useful properties - hardness, thermal and corrosion resistance, malleability, etc. .

Blast furnace iron production process

The blast-furnace process of iron production consists of the following stages:

a) preparation (roasting) of sulfide and carbonate ores - conversion to oxide ore:

FeS 2 → Fe 2 O 3 (O 2, 800 ° С, -SO 2) FeCO 3 → Fe 2 O 3 (O 2, 500-600 ° С, -CO 2)

b) burning coke with hot blast:

C (coke) + O 2 (air) → CO 2 (600-700 ° C) CO 2 + C (coke) ⇌ 2CO (700-1000 ° C)

c) reduction of oxide ore with carbon monoxide CO in succession:

Fe2O3 →(CO)(Fe II Fe 2 III) O 4 →(CO) FeO →(CO) Fe

d) carburization of iron (up to 6.67% C) and melting of cast iron:

Fe (t ) →(C(coke)900-1200°С) Fe (g) (cast iron, t pl 1145°C)

In cast iron, cementite Fe 2 C and graphite are always present in the form of grains.

Steel production

The redistribution of cast iron into steel is carried out in special furnaces (converter, open-hearth, electric), which differ in the method of heating; process temperature 1700-2000 °C. Blowing oxygen-enriched air burns out excess carbon from cast iron, as well as sulfur, phosphorus and silicon in the form of oxides. In this case, oxides are either captured in the form of exhaust gases (CO 2, SO 2), or are bound into an easily separated slag - a mixture of Ca 3 (PO 4) 2 and CaSiO 3. To obtain special steels, alloying additives of other metals are introduced into the furnace.

Receipt pure iron in industry - electrolysis of a solution of iron salts, for example:

FeCl 2 → Fe↓ + Cl 2 (90°C) (electrolysis)

(there are other special methods, including the reduction of iron oxides with hydrogen).

Pure iron is used in the production of special alloys, in the manufacture of cores of electromagnets and transformers, cast iron is used in the production of castings and steel, steel is used as structural and tool materials, including wear-, heat- and corrosion-resistant materials.

Iron(II) oxide F EO . Amphoteric oxide with a large predominance of basic properties. Black, has an ionic structure of Fe 2+ O 2-. When heated, it first decomposes, then re-forms. It is not formed during the combustion of iron in air. Does not react with water. Decomposed by acids, fused with alkalis. Slowly oxidizes in moist air. Recovered by hydrogen, coke. Participates in the blast-furnace process of iron smelting. It is used as a component of ceramics and mineral paints. Equations of the most important reactions:

4FeO ⇌ (Fe II Fe 2 III) + Fe (560-700 ° С, 900-1000 ° С)

FeO + 2HC1 (razb.) \u003d FeC1 2 + H 2 O

FeO + 4HNO 3 (conc.) \u003d Fe (NO 3) 3 + NO 2 + 2H 2 O

FeO + 4NaOH \u003d 2H 2 O + Na 4FeO3(red.) trioxoferrate(II)(400-500 °С)

FeO + H 2 \u003d H 2 O + Fe (high purity) (350 ° C)

FeO + C (coke) \u003d Fe + CO (above 1000 ° C)

FeO + CO \u003d Fe + CO 2 (900 ° C)

4FeO + 2H 2 O (moisture) + O 2 (air) → 4FeO (OH) (t)

6FeO + O 2 \u003d 2 (Fe II Fe 2 III) O 4 (300-500 ° С)

Receipt in laboratories: thermal decomposition of iron (II) compounds without air access:

Fe (OH) 2 \u003d FeO + H 2 O (150-200 ° C)

FeSOz \u003d FeO + CO 2 (490-550 ° С)

Diiron oxide (III) - iron ( II ) ( Fe II Fe 2 III) O 4 . Double oxide. Black, has the ionic structure of Fe 2+ (Fe 3+) 2 (O 2-) 4. Thermally stable up to high temperatures. Does not react with water. Decomposed by acids. It is reduced by hydrogen, red-hot iron. Participates in the blast-furnace process of iron production. It is used as a component of mineral paints ( minium iron), ceramics, colored cement. The product of special oxidation of the surface of steel products ( blackening, bluing). The composition corresponds to brown rust and dark scale on iron. The use of the Fe 3 O 4 formula is not recommended. Equations of the most important reactions:

2 (Fe II Fe 2 III) O 4 \u003d 6FeO + O 2 (above 1538 ° С)

(Fe II Fe 2 III) O 4 + 8HC1 (razb.) \u003d FeC1 2 + 2FeC1 3 + 4H 2 O

(Fe II Fe 2 III) O 4 + 10HNO 3 (conc.) \u003d 3 Fe (NO 3) 3 + NO 2 + 5H 2 O

(Fe II Fe 2 III) O 4 + O 2 (air) \u003d 6Fe 2 O 3 (450-600 ° С)

(Fe II Fe 2 III) O 4 + 4H 2 \u003d 4H 2 O + 3Fe (high purity, 1000 ° C)

(Fe II Fe 2 III) O 4 + CO \u003d 3 FeO + CO 2 (500-800 ° C)

(Fe II Fe 2 III) O4 + Fe ⇌4 FeO (900-1000 ° С, 560-700 ° С)

Receipt: combustion of iron (see) in air.

magnetite.

Iron(III) oxide F e 2 O 3 . Amphoteric oxide with a predominance of basic properties. Red-brown, has an ionic structure (Fe 3+) 2 (O 2-) 3. Thermally stable up to high temperatures. It is not formed during the combustion of iron in air. Does not react with water, a brown amorphous hydrate Fe 2 O 3 nH 2 O precipitates from the solution. Slowly reacts with acids and alkalis. It is reduced by carbon monoxide, molten iron. Alloys with oxides of other metals and forms double oxides - spinels(technical products are called ferrites). It is used as a raw material in iron smelting in the blast furnace process, as a catalyst in the production of ammonia, as a component of ceramics, colored cements and mineral paints, in thermite welding of steel structures, as a sound and image carrier on magnetic tapes, as a polishing agent for steel and glass.

Equations of the most important reactions:

6Fe 2 O 3 \u003d 4 (Fe II Fe 2 III) O 4 + O 2 (1200-1300 ° С)

Fe 2 O 3 + 6HC1 (razb.) → 2FeC1 3 + ZH 2 O (t) (600 ° C, p)

Fe 2 O 3 + 2NaOH (conc.) → H 2 O+ 2 NaFeO 2 (red)dioxoferrate(III)

Fe 2 O 3 + MO \u003d (M II Fe 2 II I) O 4 (M \u003d Cu, Mn, Fe, Ni, Zn)

Fe 2 O 3 + ZN 2 \u003d ZN 2 O + 2Fe (highly pure, 1050-1100 ° С)

Fe 2 O 3 + Fe \u003d ZFeO (900 ° C)

3Fe 2 O 3 + CO \u003d 2 (Fe II Fe 2 III) O 4 + CO 2 (400-600 ° С)

Receipt in the laboratory - thermal decomposition of iron (III) salts in air:

Fe 2 (SO 4) 3 \u003d Fe 2 O 3 + 3SO 3 (500-700 ° С)

4 (Fe (NO 3) 3 9 H 2 O) \u003d 2 Fe a O 3 + 12NO 2 + 3O 2 + 36H 2 O (600-700 ° С)

In nature - iron oxide ores hematite Fe 2 O 3 and limonite Fe 2 O 3 nH 2 O

Iron(II) hydroxide F e(OH) 2 . Amphoteric hydroxide with a predominance of basic properties. White (sometimes with a greenish tinge), Fe-OH bonds are predominantly covalent. Thermally unstable. Easily oxidizes in air, especially when wet (darkens). Insoluble in water. Reacts with dilute acids, concentrated alkalis. Typical restorer. An intermediate product in the rusting of iron. It is used in the manufacture of the active mass of iron-nickel batteries.

Equations of the most important reactions:

Fe (OH) 2 \u003d FeO + H 2 O (150-200 ° C, in atm.N 2)

Fe (OH) 2 + 2HC1 (razb.) \u003d FeC1 2 + 2H 2 O

Fe (OH) 2 + 2NaOH (> 50%) \u003d Na 2 ↓ (blue-green) (boiling)

4Fe(OH) 2 (suspension) + O 2 (air) → 4FeO(OH)↓ + 2H 2 O (t)

2Fe (OH) 2 (suspension) + H 2 O 2 (razb.) \u003d 2FeO (OH) ↓ + 2H 2 O

Fe (OH) 2 + KNO 3 (conc.) \u003d FeO (OH) ↓ + NO + KOH (60 ° С)

Receipt: precipitation from solution with alkalis or ammonia hydrate in an inert atmosphere:

Fe 2+ + 2OH (razb.) = Fe(OH) 2 ↓

Fe 2+ + 2 (NH 3 H 2 O) = Fe(OH) 2 ↓+ 2NH4

Iron metahydroxide F eO(OH). Amphoteric hydroxide with a predominance of basic properties. Light brown, Fe-O and Fe-OH bonds are predominantly covalent. When heated, it decomposes without melting. Insoluble in water. It precipitates from solution in the form of a brown amorphous polyhydrate Fe 2 O 3 nH 2 O, which, when kept under a dilute alkaline solution or when dried, turns into FeO (OH). Reacts with acids, solid alkalis. Weak oxidizing and reducing agent. Sintered with Fe(OH) 2 . An intermediate product in the rusting of iron. It is used as a base for yellow mineral paints and enamels, as an exhaust gas absorber, as a catalyst in organic synthesis.

Connection composition Fe(OH) 3 is not known (not obtained).

Equations of the most important reactions:

Fe 2 O 3 . nH 2 O→( 200-250 °С, —H 2 O) FeO(OH)→( 560-700°C in air, -H2O)→Fe 2 O 3

FeO (OH) + ZNS1 (razb.) \u003d FeC1 3 + 2H 2 O

FeO(OH)→ Fe 2 O 3 . nH 2 O-colloid(NaOH (conc.))

FeO(OH) → Na 3 [Fe(OH) 6 ]white, Na 5 and K 4, respectively; in both cases, a blue product of the same composition and structure, KFe III, precipitates. In the laboratory, this precipitate is called Prussian blue, or turnbull blue:

Fe 2+ + K + + 3- = KFe III ↓

Fe 3+ + K + + 4- = KFe III ↓

Chemical names of initial reagents and reaction product:

K 3 Fe III - potassium hexacyanoferrate (III)

K 4 Fe III - potassium hexacyanoferrate (II)

KFe III - hexacyanoferrate (II) iron (III) potassium

In addition, the thiocyanate ion NCS - is a good reagent for Fe 3+ ions, iron (III) combines with it, and a bright red (“bloody”) color appears:

Fe 3+ + 6NCS - = 3-

With this reagent (for example, in the form of KNCS salt), even traces of iron (III) can be detected in tap water if it passes through iron pipes covered with rust from the inside.

68. Iron compounds

Iron(II) oxide FeO- a black crystalline substance, insoluble in water and alkalis. FeO matches base Fe(OH)2.

Receipt. Iron oxide (II) can be obtained by incomplete reduction of magnetic iron ore with carbon monoxide (II):

Chemical properties. It is the main oxide. Reacts with acids to form salts:

Iron(II) hydroxide Fe(OH)2- white crystalline substance.

Receipt. Iron (II) hydroxide is obtained from ferrous salts by the action of alkali solutions:

Chemical properties. basic hydroxide. Reacts with acids:

In air, Fe (OH) 2 is oxidized to Fe (OH) 3:

Iron(III) oxide Fe2O3- a brown substance, occurs in nature in the form of red iron ore, insoluble in water.

Receipt. When firing pyrite:

Chemical properties. Shows weak amphoteric properties. When interacting with alkalis, it forms salts:

Iron(III) hydroxide Fe(OH)3- a substance of red-brown color, insoluble in water and excess alkali.

Receipt. Obtained by oxidation of iron oxide (III) and iron hydroxide (II).

Chemical properties. It is an amphoteric compound (with a predominance of basic properties). It precipitates under the action of alkalis on ferric salts:

Ferrous salts obtained by the interaction of metallic iron with the corresponding acids. They are strongly hydrolyzed, therefore their aqueous solutions are energetic reducing agents:

When heated above 480 °C, it decomposes, forming oxides:

Under the action of alkalis on iron (II) sulfate, iron (II) hydroxide is formed:

Forms a crystalline hydrate FeSO4?7H2O (iron vitriol). Iron (III) chloride FeCl3 – dark brown crystalline substance.

Chemical properties. Soluble in water. FeCl3 exhibits oxidizing properties.

Reducing agents - magnesium, zinc, hydrogen sulfide, are oxidized without heating.

Density 5.745 g/cm³ Thermal Properties T. melt. 1377°C T. kip. 3414°C T. dec. 560-700°C Enthalpy of formation FeO(tv): -272 kJ/mol
FeO(l): 251 kJ/mol Classification SMILES Safety NFPA 704 Data is based on standard conditions (25 °C, 100 kPa) unless otherwise noted.

Iron(II) oxide (iron oxide) is a complex inorganic compound of ferrous iron and oxygen.

Physical Properties

Black connection. Crystal lattice similar to rock salt. It has a non-stoichiometric structure with a homogeneity range from Fe 0.84 O to Fe 0.95 O. This is due to the fact that its crystal lattice is stable only when not all of its nodes are occupied by iron atoms. Stable iron oxide (II) becomes only with increasing temperature.

Being in nature

Iron(II) oxide occurs naturally as the mineral wüstite.

Receipt

  • Heating iron at low oxygen partial pressure:
\mathsf(2Fe + O_2 \xrightarrow(t) 2FeO)
  • Decomposition of iron (II) oxalate in vacuum:
\mathsf(FeC_2O_4 \xrightarrow(t) FeO + CO\uparrow + CO_2\uparrow)
  • Interaction of iron with iron oxide (III) or iron oxide (II,III):
\mathsf(Fe + Fe_2O_3 \xrightarrow(900^oC) 3FeO)
\mathsf(Fe + Fe_3O_4 \xrightarrow(900-1000^oC) 4FeO)
  • Recovery of iron(III) oxide with carbon monoxide:
\mathsf(Fe_2O_3 + CO \xrightarrow(500-600^oC) 2FeO + CO_2\uparrow)
  • Thermal decomposition of iron oxide (II, III):
\mathsf(2Fe_3O_4 \xrightarrow(>1538^oC) 6FeO + O_2\uparrow)
  • Thermal decomposition of iron (II) hydroxide without air access:
\mathsf(Fe(OH)_2 \xrightarrow(150-200^oC) FeO + H_2O)
  • Thermal decomposition of iron (II) carbonate without air access:
\mathsf(FeCO_3 \xrightarrow(t) FeO + CO_2\uparrow)

Chemical properties

\mathsf(4FeO \xrightarrow( 200 -565^oC) Fe_3O_4 + Fe)
  • Interaction with dilute hydrochloric acid:
\mathsf(FeO + 2HCl \longrightarrow FeCl_2 + H_2O)
  • Interaction with concentrated nitric acid:
\mathsf(FeO + 4HNO_3 \longrightarrow Fe(NO_3)_3 + NO_2 + 2H_2O)
  • Fusion with sodium hydroxide:
\mathsf(FeO + 4NaOH \xrightarrow(400-500^oC) Na_4FeO_3 + 2H_2O)
  • Interaction with oxygen:
\mathsf(4FeO + 2nH_2O + O_2 \rightarrow 2(Fe_2O_3\cdot nH_2O)) \mathsf(6FeO + O_2 \xrightarrow(300-500^oC) 2Fe_3O_4)
  • Interaction with hydrogen sulfide:
\mathsf(FeO + H_2S \xrightarrow(500^oC) FeS + H_2O)
  • Recovery with hydrogen and coke:
\mathsf(FeO + H_2 \xrightarrow(350^oC) Fe + H_2O) \mathsf(FeO + C \xrightarrow(>1000^oC) Fe + CO)

Application

  • Participates in the blast-furnace process of iron smelting.
  • It is used as a component of ceramics and mineral paints.
  • In the food industry, it is widely used as a food coloring under the number E172.

The formation of a strong thin layer of iron(II) oxide on the surface of steel is the result of a process called bluing (blackening). By adjusting the thickness of this layer, in addition to black, any tint colors can be achieved. On this property of iron(II) oxide, the technology for obtaining color patterns on steel is built.

Toxicity

Aerosols (dust, smoke) of iron oxide (II) with prolonged exposure are deposited in the lungs and cause siderosis - a type of pneumoconiosis with a relatively benign course.

see also

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Literature

  • Lidin R. A. “Handbook of a student. Chemistry "M.: Asterel, 2003.
  • Volkov A.I., Zharsky I.M. Big chemical reference book / A.I. Volkov, I.M. Zharsky. - Minsk: Modern school, 2005. - 608 p.
  • Lidin R.A. and other Chemical properties of inorganic substances: Proc. allowance for universities. 3rd ed., Rev./R.A. Lidin, V.A. Molochko, L.L. Andreeva; Ed. R.A. Lidina. - M.: Chemistry, 200. 480 p.: ill.
  • Greenwood N. Chemistry of elements: in 2 volumes.
  • .Greenwood, A. Earnshaw; per. from English. - M.: BINOM. Knowledge Laboratory, 2011. - (The best foreign textbook)
  • Harmful chemicals. Inorganic compounds of groups V-VIII: Ref. ed./ A.L. Bandman, N.V. Volkova, T.D. Grekhova and others; Ed. V.A. Filova and others - L.: Chemistry, 1989. 592 p.
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An excerpt characterizing Iron(II) oxide

Natasha blushed purple upon hearing these words.
- How blushing, how blushing, ma delicieuse! [my charm!] - Helen said. - You should definitely come. Si vous aimez quelqu "un, ma delicieuse, ce n" est pas une raison pour se cloitrer. Si meme vous etes promise, je suis sure que votre promis aurait desire que vous alliez dans le monde en son absence plutot que deperir d "ennui. [From the fact that you love someone, my lovely, you should not live as a nun. Even if you're a bride, I'm sure your fiancé would rather have you go out into the world in his absence than die of boredom.]
“So she knows that I am a bride, so she and her husband, with Pierre, with this fair Pierre, Natasha thought, talked and laughed about it. So it was nothing." And again, under the influence of Helen, what had previously seemed terrible seemed simple and natural. “And she is such a grande dame, [important lady,] so sweet and so evidently loves me with all her heart,” thought Natasha. And why not have fun? thought Natasha, looking at Helen with surprised, wide-open eyes.
Marya Dmitrievna returned to dinner, silent and serious, obviously having suffered a defeat at the old prince's. She was still too excited about the collision to be able to calmly tell the story. To the question of the count, she answered that everything was fine and that she would tell tomorrow. Learning about the visit of Countess Bezukhova and the invitation to the evening, Marya Dmitrievna said:
- I don’t like to hang out with Bezukhova and I won’t advise; Well, yes, if you promised, go, you’ll be scattered, ”she added, turning to Natasha.

Count Ilya Andreich took his girls to Countess Bezukhova. There were quite a lot of people at the evening. But the whole society was almost unfamiliar to Natasha. Count Ilya Andreich noted with displeasure that this whole society consisted mainly of men and women, known for their liberties of treatment. M lle Georges, surrounded by young people, stood in the corner of the living room. There were several Frenchmen, among them Metivier, who, since Helene's arrival, had been her housewife. Count Ilya Andreich made up his mind not to sit down at cards, not to leave his daughters, and to leave as soon as the performance of Georges was over.
Anatole was apparently at the door waiting for the Rostovs to enter. He immediately greeted the count, went up to Natasha and followed her. As soon as Natasha saw him, just as in the theater, a feeling of conceited pleasure that he liked her and fear from the absence of moral barriers between her and him seized her. Helen joyfully received Natasha and loudly admired her beauty and toilet. Shortly after their arrival, m lle Georges left the room to dress. In the living room they began to arrange chairs and sit down. Anatole moved a chair to Natasha and wanted to sit beside her, but the count, who did not take his eyes off Natasha, sat down beside her. Anatole sat in the back.
M lle Georges, with bare, dimpled, thick arms, in a red shawl worn over one shoulder, stepped into the empty space left for her between the chairs and stopped in an unnatural pose. An enthusiastic whisper was heard. M lle Georges looked sternly and gloomily at the audience and began to speak some verses in French, where it was about her criminal love for her son. In places she raised her voice, in places she whispered, solemnly raising her head, in places she stopped and wheezed, rolling her eyes.
- Adorable, divin, delicieux! [Amazing, divine, wonderful!] - was heard from all sides. Natasha looked at fat Georges, but heard nothing, saw nothing, and understood nothing of what was going on in front of her; she only felt completely irrevocable again in that strange, insane world, so far from the former, in that world in which it was impossible to know what was good, what was bad, what was rational and what was insane. Behind her sat Anatole, and she, feeling his closeness, fearfully waited for something.
After the first monologue, the whole society stood up and surrounded m lle Georges, expressing their delight to her.
- How good she is! Natasha said to her father, who, along with the others, got up and moved towards the actress through the crowd.
“I can’t find it, looking at you,” Anatole said, following Natasha. He said it at a time when she alone could hear him. - You are charming ... from the moment I saw you, I did not stop ....
“Let’s go, let’s go, Natasha,” said the count, returning for his daughter. - How good!
Natasha, without saying anything, went up to her father and looked at him with questioning surprised eyes.
After several receptions of recitation, m lle Georges left and the Countess Bezuhaya asked for company in the hall.
The count wanted to leave, but Helen begged not to spoil her impromptu ball. The Rostovs remained. Anatole invited Natasha to a waltz, and during the waltz, he, shaking her body and hand, told her that she was ravissante [charming] and that he loved her. During the ecossaise, which she again danced with Kuragin, when they were alone, Anatole did not say anything to her and only looked at her. Natasha was in doubt if she saw in a dream what he said to her during the waltz. At the end of the first figure, he again shook hands with her. Natasha looked up at him with frightened eyes, but such a self-confidently gentle expression was in his affectionate look and smile that she could not, looking at him, say what she had to tell him. She lowered her eyes.
“Don't tell me such things, I'm engaged and in love with another,” she said quickly ... - She looked at him. Anatole was not embarrassed or upset by what she said.
- Don't tell me about it. What is my business? - he said. “I'm saying I'm madly, madly in love with you. Is it my fault that you are amazing? We start.
Natasha, animated and anxious, looked around her with wide, frightened eyes and seemed more cheerful than usual. She hardly remembered anything from what had happened that evening. Ecossaise and Gros Vater danced, her father invited her to leave, she asked to stay. Wherever she was, whoever she spoke to, she could feel his eyes on her. Then she remembered that she had asked her father's permission to go into the dressing room to straighten her dress, that Helen had gone out to fetch her, told her laughing about her brother's love, and that she had met Anatole again in the little sofa room, that Helen had disappeared somewhere, they were left alone and Anatole, Taking her by the hand, he said in a gentle voice:
“I can’t visit you, but will I never see you again?” I love you madly. Really never? ... - and he, blocking her way, brought his face closer to her face.
His brilliant, large, masculine eyes were so close to hers that she could see nothing but those eyes.
- Natalie? his voice whispered inquiringly, and someone squeezed her hands painfully.
- Natalie?
"I don't understand anything, I have nothing to say," her look said.
Hot lips pressed against hers, and at that very moment she felt free again, and the sound of steps and Helen's dress was heard in the room. Natasha looked back at Helen, then, red and trembling, looked at him in frightened questioning and went to the door.
- Un mot, un seul, au nom de Dieu, [One word, only one, for God's sake,] - said Anatole.
She stopped. She so needed him to say that word, which would explain to her what had happened and to which she would answer him.
“Nathalie, un mot, un seul,” he repeated everything, apparently not knowing what to say, and repeated it until Helen approached them.
Helen went out into the living room again with Natasha. Not staying for supper, the Rostovs left.
Returning home, Natasha did not sleep all night: she was tormented by the insoluble question of whom she loved, Anatole or Prince Andrei. She loved Prince Andrei—she remembered clearly how much she loved him. But she loved Anatole too, that was beyond doubt. “Otherwise, how could all this be?” she thought. “If after that I could, after saying goodbye to him, answer his smile with a smile, if I could allow it to happen, it means that I fell in love with him from the first minute. It means that he is kind, noble and beautiful, and it was impossible not to love him. What should I do when I love him and love another? she said to herself, finding no answers to these terrible questions.