IRON
Due to formation of non-porous oxide layer the metal becomes chemically inactive.
FeCl3 is formed because (Cl2) is oxidizing agent.
Iron oxides
A) Iron II oxide FeO
Iron II oxide is basic oxide because it reacts with acids forming salt and water.
IRON
Reactions:
Iron III oxide is basic because it reacts with acids giving salt and water. Its reactions take
place with hot conc. acids because the oxidation number of iron in iron III oxide is (+3) , i.e. It
is rationally stable as it contains 5 electrons in orbital 3d.
C) Magnetic Iron oxide Fe3O4
Preparation:
Reactions:
It reacts as a complex oxide that gives two kind of salts.
GR: Magnetic iron oxide reacts with conc. acids to give two kinds of salts?
Detection of Iron (II) and iron (III) cations
1) Iron (II) cations Fe2+:
2) Iron (III) cation Fe3+:
A. Give reasons for:
1- Scandium has limited uses.
1- Because it is not abundant element in the earth's crust.
2- Titanium is preferred in the manufacture of rockets and supersonic air- crafts.
.
IRON
2- Because it can keep strength at high pressure and temperature.
3- Vanadium is used in the manufacture of steel.
3- Because it gives the steel hardness and corrosion resistance.
4- Vanadium is used in the manufacture of car springs.
4- Because it has corrosion resistance and not rust.
5- Chromium is highly reactive but it resists the effect of atmosphere.
5- Due to the formation of non- porous oxide layer on its surface which prevent farther reaction with oxygen in the air.
6- Chromium is used to plate other metals.
6- To resist corrosion and make them more attractive.
7- Manganese is used in the production of steel.
7- Because it reacts with oxygen during production process to prevent the formation of bubbles in steel during cooling.
8- Cobalt II chloride is used in the manufacture of secret ink.
8- Because aqueous solution of cobalt II chloride has a pale pink colour which does not appear in writing, then changing
to deep blue colour on dehydration by heating therefore the writing appears:
9- Anhydrous cobalt II chloride is used in atmospheric prediction.
9-
Because a certain paper are covered with blue cobalt II chloride when turned to pale pink, this indicate that the
increase in relative humidity in air and possibility of raining.
10- Nickel is used in plating metals.
10- To protect them from oxidation and corrosion and to give them a shiny coating.
11- Caustic soda and liquid hydrogen fluoride are kept or stored in containers made of nickel.
11- Due to its resistance to corrosion and it is not affected by them.
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12- Chromium and copper are anomalous (abnormal) - in their electronic configuration than the expect one.
12- In case of chromium
one electron is transferred from (4S) sublevel to 3d sublevel so the sublevels (4S)
and (3d) become half filled. This makes the atom has less energy and more stable.
- In case of copper
one electron is transferred from (4S) sublevel to (3d) sublevel so the sublevel (4s) become half filled and the
sublevel (3d) become complete filled, this makes the atom has less energy and more stable
13- Iron II is easily oxidized to iron III while Mn II is not easily oxidized to Mn III.
13- Because iron III is more stable than iron II , 3d sublevel is half filled with electrons
While Mn II is more stable than Mn III because 3d sublevel in Mn II is half filled with electrons therefore Mn II
difficult to oxidized to Mn III.
14- The elements of the first transition series loses its (4s) electrons before the (3d) electrons.
14- Because the 4s sublevel is the outermost one therefore on oxidation the atom usually loses (4s) electron first then electrons of (3d).
15- The oxidation number of the 1st series of the transition elements is (2+).
15- Because when they gain energy they will loses two electrons from the sublevel (4s) at first.
16- Scandium
cannot give oxidations state (2+) but it give the oxidation state (3+) only.
16- Because when the atom gains energy it loses two electrons from the sublevel (4s) then one electron from (3d) sublevel
to be more stable as [Ar18].
17- Transition elements are characterized by having variable oxidation states.
17- Because the two sublevels (4s) and (3d) of nearly equal energy and their electrons are lost in sequence when the atom is oxidized.
18- Scandium can not give the oxidation number (4+).
18- Because the amount of energy needed to obtain this ion is greater due to the breaking of complete energy level.
IRON
19- The coinage metals which are
are considered as transition although the orbitals of (d)
sublevel are completely filled with electrons.
19- Because in their higher oxidation states
contain (9) or (8) electron in (d)
sublevel.
20- Transition elements used in the manufacture of alloys.
20- Because these elements have nearly equal atomic radius and give desired properties when they form alloys.
21- It is difficult to oxidize the elements of the end of the transition series.
21- Because their outer most shell are completely filled with electrons so they have a stable electronic configuration
22-
are non-transition elements.
22- Because the orbitals of (d) sublevel are completely filled with electrons in their free states or in their higher oxidation states.
23- The densities of transition elements increase with the increase of atomic number.
23- Due to the increase of the atomic mass while the atomic radius is nearly constant.
24- The transition elements have high melting and boiling point.
24- Because they have strong metallic bonds, resulting from sharing of both the (4s) and (3d) electrons.
25- The transition elements are paramagnetic elements.
25- Due to the presence of unpaired electrons in the orbitals of (d) sublevel. example:
26- Ions of non-transition elements are colorless.
26- Because the orbitals of the (d) sublevel are empty or completely filled with electrons. So, they can absorb all colour if light or reflect
them.
27- The transition elements have a catalytic activity.
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27- Due to the presence of unpaired electrons in the orbitals of (d) sublevel which can be used in the formation of bonds
between the reactants molecules and the atoms of the metal surface therefore the concentration of the reactants
molecules increases so the speed of the reaction increase.
28- When iron reacts with chlorine iron (III) chloride is formed and not iron (II) chloride .
28- Because chlorine act as oxidizing agent, helps in formation of FeCl 3 and prevent formation of FeCl2
.
29- When iron reacts with diluted acids iron II salts are formed.
29- Due to the evolution of hydrogen gas which act as reducing agent. reduces FeCl 3 into FeCl2
.
30- Iron magnetic oxide reacts with conc. acids to give two kind of salts.
30- Because this kind of oxide react as two oxides (i.e) react as FeO and
31- When iron II oxalate in heated strongly FeO is formed and not
.
31- Due to the presence of CO gas which act as reducing agent, prevents formation of Fe 2O3
32- When iron II oxalate is formed a black ppt. is formed 32- Due to the formation of a black iron
II oxide (FeO)
33- When green vitroil is heated strongly its colour is changed from green to brick red colour. 33Due to the formation of iron III oxide (Hematite) which has a brick red colour
IRON
B- Write the scientific expression for each of the following
1- A process of heating iron ores in air for expelting humidity and
before its reduction in the blast furnace.
1- Roasting process.
2- Elements that have all their electrons in paired.
2- Diamagnetic elements.
3- A process in which purification of iron ores takes place by adding water and oil and passing strong air.
3- Air flotation process.
4- Elements that have partially filled (f) sublevel.
4- Inner transition elements.
5- Elements that have partially filled (d) sublevel.
5- Main transition elements.
6- Elements in which the (d) or (f) sublevels are one of their oxidation states.
6- the transition elements.
7- A process of converting the large size of the iron are to small sized suitable for reduction process.
7- Crushing process.
8- A process of converting of the fine particles of the iron ore to a large particle suitable for reduction process.
8- Sintering process.
9- A substance that is attracted to the magnet due to the presence of unpaired electrons in (d) sublevel.
9- paramagnetic substance.
10- A substance that is repelled with the magnet due to the presence of all its electrons in paired state.
IRON
10- Diamagnetic substance.
11- A mixture of two metals or more in a certain ratio.
11- Alloys.
E. Choose the correct answer
1- Iron II oxide can be obtained by: a- Heating iron II oxalate in absence of
air
b- Heating iron II sulphate
c- Heating iron III oxide in absence of air.
d- heating iron III sulphate
2- Element has electronic configuration
its maximum oxidation number is:
a- (7+),
b- (5+),
c- (3+),
d- (2+)
3- On heating green vitroil crystals strongly, the following observation are noted.
a- green vitroil loses its water of crystallization only.
b- Iron III oxide is formed.
c- acidic gases are evolved.
d- all previous
4- On passing steam over red hot iron we obtain
a- iron III oxide
b- Iron II oxide
c- Magnetic iron oxide
d- a and b 5Substitutional alloys are formed of elements having:
a- The same diameter
b- The same crystalline structure
c- The same chemical
properties
d- (a), (b) and (c) 6- Element has the atomic number (29) its electronic
configuration is:
a-
b-
c-
e-
7 Element has the
the element is:
electronic structure a- Paramagnetic in its maximum oxidation states.
Diamagnetic in its atomic state.
c- Paramagnetic when its oxidation number is (4).
b-
d- Coloured in its maximum oxidations states.
8- Elements has the electronic configuration
a- A main transition element
c- One of lanthanide series
the element is:
b- An inner transition element
d- one of actinides series
9- Element has the electronic configuration
a- more than one oxidation state
the element has
b- catalytic activity
c- coloured compounds
d- a, b and c
10- Element has the electronic configuration
f block elements
b- S-block elements
the element belongs to a-
IRON
c- Representative elements
d- d- block elements
C. Complete the following:
12- In the oxygen converter the charge is ...............
2- Molten big iron
3- ................. is used in the manufacture of secret ink whereas .......... is used in the manufacture of
rockets and aero planes.
3- anhydrous cobalt II chloride - Titanium
4- When iron fillings are heated strongly in air .............. is formed which reacts with ............. to form two types of salts.
4- iron magnetic oxide
- conc. acids
5- When iron is heated with Sulphur .............. is formed which reacts with sulphuric acid giving .................. gas
turns a paper wet with .............. to a black.
6- When iron reacts with conc. heated
7-
8-
9-
10-
..............., ..................., ............. and ................ are formed.
IRON
10D. Put (true) or (false) and correct the wrong one.
1- Chromium metal resists the action of atmospheric effects although it is chemically active.
(
)
2- The anhydrous cobalt II chloride is used in atmospheric predictions because the humidity turns its colour from pale pink to blue.
2- (
) turns the colour from blue to pale pink.
3- Copper and gold form together a substitutional alloy. (
)
4- Compounds of iron III are more stable than compounds of iron II because the latter are easily oxidized. (
5- On strong heating of green vitroil two forms of Sulphur oxides are formed.
6- Vanadium ion
is colored. 6- (
)
) colorless
7- On passing chlorine gas on hot iron, iron II chloride is formed. 7- (
)
8- In midrex furnace carbon monoxide gas can be used as reducing agent. 8- (
9- When iron fillings reacts with Sulphur iron (III) sulphide is formed. 9- (
10-
(
)
) mixture of CO and
)iron (II) sulphide
Iron magnetic oxide reacts with dil. acids to form iron (II) salts and water. 10- (
water.
) iron (II) and iron (III) slats and
Short notes
IRON: REACTIONS OF ELEMENTS
1.1 REACTION OF IRON WITH AIR
Iron metal reacts in moist air by oxidation to give a hydrated iron oxide. This does not protect the iron surface to
further reaction since it flakes off, exposing more iron metal to oxidation. This process is called rusting and is
familiar to any car owner. Finely divided iron powder is pyrophoric, making it a fire risk.
On heating with oxygen, O2, the result is formation of the iron oxides Fe2O3 and Fe3O4.
4Fe(s) + 3O2(g) → 2Fe2O3(s)
3Fe(s) + 2O2(g) → Fe3O4(s)
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1.2 REACTION OF IRON WITH WATER
Air-free water has little effect upon iron metal. However, iron metal reacts in moist air by oxidation to give a hydrated iron
oxide. This does not protect the iron surface to further reaction since it flakes off, exposing more iron metal to oxidation. This
process is called rusting and is familiar to any car owner.
1.3 REACTION OF IRON WITH THE HALOGENS
Iron reacts with excess of the halogens F2, Cl2, and Br2, to form ferric, that is, Fe(III), halides.
2Fe(s) + 3F2(g) → 2FeF3(s) (white)
2Fe(s) + 3Cl2(g) → 2FeCl3(s) (dark brown)
2Fe(s) + 3Br2(l) → 2FeBr3(s) (reddish brown)
This reaction is not very successful for iodine because of thermodynamic problems. The iron(III) is too oxidizing
and the iodide is too reducing. The direct reaction between iron metal and iodine can be used to prepare iron
(II) iodide, FeI2.
Fe(s) + I2(s) → FeI2(s) (grey)
1.4 REACTION OF IRON WITH ACIDS
Iron metal dissolves readily in dilute sulphuric acid in the absence of oxygen to form solutions containing the equated Fe(II)
ion together with hydrogen gas, H2. In practice, the Fe(II) is present as the complex ion [Fe(OH2)6]2+.
Fe(s) + H2SO4(aq) → Fe2+(aq) + SO42-(aq) + H2(g)
If oxygen is present, some of the Fe(II) oxidizes to Fe(III).
The strongly oxidizing concentrated nitric acid, HNO3, reacts on the surface of iron and passivates the surface.
Additional knowledge about iron
Under anaerobic conditions, ferrous hydroxide (Fe(OH)2) can be oxidized by water to form magnetite and molecular
hydrogen. This process is described by the Schikorr reaction:
The well-crystallized magnetite (Fe3O4) is thermodynamically more stable than the ferrous hydroxide (Fe(OH)2).
Magnetite can be prepared in the laboratory as a ferrofluid in the Massart method by mixing iron(II) chloride
and iron(III) chloride in the presence of sodium hydroxide.[6] Magnetite can also be prepared by the chemical
co-precipitation in presence of ammonia, which consist in a mixture of a solution 0.1 M of FeCl3·6H2O and
FeCl2·4H2O with mechanic agitation of about 2000 rpm. The molar ratio of FeCl3:FeCl2 can be 2:1; heating this
solution at 70 °C, and immediately the speed is elevated to 7500 rpm and adding quickly a solution of NH4OH
(10 volume %), immediately a dark precipitate will be formed, which consists of nanoparticles of magnetite.[7]
In both cases, the precipitation reaction rely on a quick transformation of acidic hydrolyzed iron ions into the
spinel iron oxide structure, by hydrolysis at elevated pH values (above ca. 10).
Reduction of Fe2O3 with hydrogen:
3Fe2O3 + H2 → 2Fe3O4 +H2O
Reduction of Fe2O3 with CO:
3Fe2O3 + CO → 2Fe3O4 + CO2
Production of Nano-particles can be performed chemically by taking for example mixtures of FeII and FeIII salts and
mixing them with alkali to precipitate colloidal Fe3O4. The reaction conditions are critical to the process and
determine the particle size.
IRON
REACTIONS
Reduction of magnetite ore by CO in a blast furnace is used to produce iron as part of steel production process:[3]
Fe3O4 + 4CO →
3Fe + 4CO2
Controlled oxidation of Fe3O4 is used to produce brown pigment quality γ-Fe2O3 (maghemite)
2Fe3O4 + ½ O2 →
3(ʎ-Fe2O3)
Magnetite
More vigorous calcining (roasting in air) gives red pigment quality α-Fe2O3 (hematite)
2Fe3O4 + ½ O2 →
3(α-Fe2O3)
hematite
IRON(III) OXIDE
Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main
oxides of iron, the other two being iron(II) oxide (FeO), which is rare, and iron(II,III) oxide (Fe3O4), which also
occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of iron
for the steel industry. Fe2O3 is ferromagnetic, dark red, and readily attacked by acids. Iron(III) oxide is often
called rust, and to some extent this label is useful, because rust shares several properties and has a similar
composition. To a chemist, rust is considered an ill-defined material, described as hydrated ferric oxide.
HYDRATED IRON(III) OXIDES
Several hydrates of Iron(III) oxide exists. When alkali is added to solutions of soluble Fe(III) salts, a red-brown
gelatinous precipitate forms. This is not Fe(OH)3, but Fe2O3·H2O (also written as Fe(O)OH). Several forms of the
hydrated oxide of Fe(III) exist as well. The red lepidocrocite γ-Fe(O)OH, occurs on the outside of rusticles, and
the orange goethite, which occurs internally in rusticles. When Fe2O3·H2O is heated, it loses its water of
hydration. Further heating at 1670 K converts Fe 2O3 to black Fe3O4 (FeIIFeIII2O4), which is known as the mineral
magnetite. Fe(O)OH is soluble in acids, giving [Fe(OH2)6]3+. In concentrated aqueous alkali, Fe2O3 gives
[Fe(OH)6]3−.
REACTIONS
The most important reaction is its carbothermal reduction, which gives iron used in steel-making:
Fe2O3 + 3 CO → 2 Fe + 3 CO2
Another redox reaction is the extremely exothermic thermite reaction with aluminum.
2 Al + Fe2O3 → 2 Fe + Al2O3
This process is used to weld thick metals such as rails of train tracks by using a ceramic container to funnel the
molten iron in between two sections of rail. Thermite is also used in weapons and making small-scale cast-iron
sculptures and tools.
IRON
Partial reduction with hydrogen at about 400 °C produces magnetite, a black magnetic material that contains
both Fe(III) and Fe(II):
3 Fe2O3 + H2 → 2 Fe3O4 + H2O
Iron(III) oxide is insoluble in water but dissolves readily in strong acid, e.g. hydrochloric and sulfuric acids. It
also dissolves well in solutions of chelating agents such as EDTA and oxalic acid.
Heating iron(III) oxides with other metal oxides or carbonates yields materials known as ferrates:[12]
ZnO + Fe2O3 → Zn(FeO2)2
PREPARATION
Iron(III) oxide is a product of the oxidation of iron. It can be prepared in the laboratory by
electrolyzing a solution of sodium bicarbonate, an inert electrolyte, with an iron anode: 4
Fe + 3 O2 + 2 H2O → 4 FeO(OH)
The resulting hydrated iron(III) oxide, written here as Fe(O)OH, dehydrates around 200 °C.
2 FeO(OH) → Fe2O3 + H2O
EXTRACTION OF IRON
Iron is extracted from its oxide ore called HAEMATITE (Fe2O3).
PRINCIPLE OF EXTRACTION
The process of the extraction of iron is carried out by the following steps:
IRON
Concentration of ore
Calcination or Roasting of ore
Reduction of ore
Concentration of ore:
In this metallurgical operation, the ore is concentrated by removing impurities like soil etc. The
process involves the crushing and washing of ore.
Calcination or Roasting of ore:
The concentrated ore is now heated in the presence of air. The process of roasting is performed
to remove moisture, CO2, impurities of Sulphur, arsenic. Ferrous oxide is also oxidized to ferric
oxide.
Reduction of ore
The process of reduction is carried out in a blast furnace.
The blast furnace is a cylindrical tower like structure about 25m to 35m high. It has an outer
shell of steel. Inside of furnace is lined with fire bricks. The top of the furnace is closed by a
cup-cone feeder.
The charge
The charge consists of :
roasted ore
Coke
IRON
Limestone
Details of reduction
The charge is fed into the furnace from its top. A preheated blast of air at 1500 OC, is blown into the furnace
under pressure near to the bottom. The blast oxidizes carbon to CO 2.
C + O2 → CO2 + heat
Formation of CO2 is an exothermic reaction in which a huge amount of heat is liberated which rises the
temperature to 1900OC in this region. As the CO2 passes upwards, it reacts more coke to form carbon
monoxide.
CO2 + C → 2CO + heat
Formation of CO is an endothermic reaction and the temperature in this region falls to 1100 OC.
CO is the main reducing agent in the upper portion of blast furnace.
Reactions in blast furnace
Fe2O3 + 3C → 2Fe + 3CO
Fe3O4 + 4CO → 3Fe + 4CO2
CO2 + C → 2CO v
Overall reaction
Fe2O3 + 3CO → 2Fe + 3CO2
The liquid iron runs downward to the bottom of the furnace and is withdrawn through tap hole.
Slag formation
Lime stone on heating decomposes to CaO and CO2.
CaCO3 →
CaO + CO2
CaO now reacts the impurities of ore called GANGUE to form slag. Slag is the mixture of CaSiO3
and Ca(AlO2)2. The slag floats over the top of molten iron. Slag is a useful byproduct. It is used in
road making, cement manufacturing a light weight building material.
Flux + Gangue → Slag
CaO + SiO2 → CaSiO3
CaO + Al2O3 → Ca(AlO2)2