Chemistry of Aluminium

7/27/2019 Chemistry of Aluminium

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INORGANIC CHEMISTRY II

CHEMISTRY OF ALUMINIUM

BY:

DWI HARKITA NINGRUM (1113031080)

I GUSTI AGUNG AYU RUSSMALLA DEWI (1113031082)

I GUSTI AYU AGUNG CYNTHIA PUTRI (1113031088)

CHEMISTRY EDUCATION DEPARTMENT

MATHEMATICS AND SCIENCCES FACULTY

GANESHA UNIVERSITY OF EDUCATION

2013


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CHEMISTRY OF ALUMINIUM

Aluminium is the commonest metallic element in the earth crust and

occurs in rocks such as feldspar and micas Cotton, 1995: 357). Aluminium has

excellent resistance to corrosion due to the thin layer of aluminium oxide that

forms on the surface of aluminium when it is exposed to air. Aluminium is a

popular choice of material for complex sectioned hollow extrusions. Aluminium is

much more metallic than boron and forms a greater number and variety of ionic

substances. Aluminium can be easily fabricated into various forms such as foil,

sheets, geometric shapes, rod, tube and wire. This essay will explain briefly the

history, abundance, isolation, uses, properties of aluminium, hydrides and their

complexes, carbides and nitrides, halides and their complexes, oxide and chalconides,

hydroxides, spinnel and aluminates, salts of oxyacid.

Aluminium derives its name from alum, the double sulfate KAL(SO4)2 .

12H2O, which was used medicinally as an astringent in ancient Greece and Rome

(latin alumen, bitter salt). Humphry Davy was unable to isolate the metal

proposed the name aluminum and then aluminium, this was soon modified to

aluminium modified to aluminium and this form is used throughout the worl

except in North America where the ACS decided in 1925 to adopt aluminium in

its publication. The impure metal was first isolated by the Danish scientist H.C

Oersted using the reaction of potassium amalgam on AlCl3. This method was

improve in 1827 by H. Wohler who used metallic potassium, but the firs

commercially successful processwas devised by H. St.C Deville in 1854 using

sodium. In the same year both he and R. W Bunsen independently obtained

metallic aluminium by electrolysis of fused NaAlCl4. 1n 1855, Emperor LouisNapoleon III used Al cutlery on state occasions. By W. Siements in 1870,

aluminium it is used as cheap electric power the development of dynamo and

secondly to the independent development in 1886 electrolysis of alumina

dissolved in cryolite by P.L.T Heroult in France and C.M Hall the USA. World

production rose quickly and 1879 exceeded 1000 tones pa for the first time

(Greenwood, 199: 216)


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Aluminium is the most abundant metal in the earth crust (8.3% by weight),

it is exceeded in abundance only by O (45.5%) and Si (25.7%) and is approached

only by Fe (6.2%) and Ca (4.6%) (Enhag:2004). Aluminium is a major constituent

of many common igneous minerals including feldspars and mics. The most

important of aluminum production is bauxite, which is hydrated aluminum oxide

containing 50 to 60% Al2O3, 1 to 20% Fe2O3, 1 to 10% silicate little titanium,

zirconium, vanadium, and other transition metal oxides, and the rest 20 to 30%

water.

Properties

Aluminium is a silvery white metal with many desirable properties. It is

one of the two common metals having electrical conductivity high enough for use as

an electrical conductor. The conductivity of electrical conductor grade (alloy 1350) is

about 62% that of the International Annealed Copper Standard. Aluminium has non-

magnetic properties which make it useful for electrical shielding such as busbar or

magnetic compass housings. The fact that aluminium is essentially nontoxic was

discovered in the early days of the industry. It is this characteristic which enables the

metal to be used in cooking utensils without any harmful effect on the

body(Mathers,2002). Aluminium with its smooth surface is easily cleaned,

promoting a hygienic environment for food processing. Selected atomic properties of

aluminium are given in the following table.

The Atomic Properties of Aluminium

Atomic number 13

Period in periodic table 3

Group in periodic table III A

Color Silver

Classification Metallic

Atomic weight 26.981538

Electron configuration 1s 2s 2p 3s 3p

Ionization energy/ kJ mol-1 I. 577.5

II. 1816.7

III. 2744.8


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Physical Properties of Aluminium

Melting Point/ 0C 660.45

Boiling Point/ 0C 2520

Density (200C)/gcm-3 2.699

Hardness (Mohs) 2.75

Hfus/kJ mot-1 10.71

Hvap/kJ mot-1 294

Hf(monoatomic gas)/kJ mol-1 329.7

Electrical resistivity/ ohm cm 2.655

E0(M3+ + 3e- = M(s))/V -1.676

E0(M+ + 3e- = M(s))/V 0.55

Electronegativity 1.5

Aluminium is easily to burn and produce high of reaction heat. The

reaction as follows:

2 Al + 3/2 O2 Al2O3

This properties is used as the basic to reduction of sulphide and oxide. Example:

2Al + Fe2O3 2Fe + Al2O3 + 199 k.cal

Aluminium is react with acid to produce hydrogen gas. The reaction as follows:

2Al(s) + 6 H+

(aq) 2Al3+

(aq) + 3H2

It has properties to produce hydrogen gas when react with strong base. The

reaction as follow

2Al(s) + 2OH-

(aq) + 2H2O 2AlO-2 + 3H2 (Kirna;2002)

Isolation

In 1825, Oersted was obtained pure aluminium by reduction of aluminium

chloride with amalgana potassium-mercurium. By destilation mercury can

separate and get aluminium metal.

AlCl3(s) + 3K(Hg)x(l) 3KCl(s) + Al(Hg)3x(l)

The isolation of aluminium can get from bauxite by two processes namely

Bayer and Hall-Heroult process. In the Bayer process, the bauxite is purifying to get


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the aluminium oxide. Second step is Hall-Heroult process by molten of aluminium

dioxide to get the pure aluminium.

Hall-Heroult

Bayer Process Process

Bayer process consist of three steps, namely extraction, precipitation, and

calcinations (Anonymous, 2009). In extraction process, the bauxite is broke by

mechanic and then dissolve in aluminium oxide become aluminium hydroxide ,

Al(OH)3. Remain of more OH- that will produce [Al(OH)4]-

Al2O3 + 2OH- +3H2O ]-(aq)

SiO2 that contain in bauxite is react with NaOH. The reaction as follows:

SiO2 + 2OH- SiO3

2-(aq) +H2O(l)

Al(OH)4-(aq) + CO2 Al(OH)3(s) + CO3

2-(aq) + H

+

The other component except aluminium oxide is not dissolve. So the aluminium

oxide will be separated from interference of Fe. This separation can be done by

filtration. After the separation, it interferences which not dissolve will enter to the

precipitation process. The filtrate that contain of aluminium hydroxide is cooling,the produce solid white precipitate. Next step is calcinations, solid white

precipitate of aluminium hydroxide is heat in the temperature 10500C. In this

step, the heating of aluminium hydroxide will decomposition become alumina and

produce vapour in its process. (Brawijaya,2009)

Al(OH)3(s) Al2O3(s) + 3H2O

Aluminium was obtained by Hall-Heroult process. In the second steps ,

electrolysis of Al2O3. Electrolysis cell is made from steel that coated withgraphite. This graphite has function as anode and cathode that formed from

carbon. Al2O3 is dissolve in kryolite (Na3AlF6). The reaction in electrode can

write as follow:

Cathode: AlF4-(aq) + 3e Al(s) + 4F

-(aq) or

2Al3+ + 6e 2Al(s)

Anode : 2AlOF54- (aq) + C CO2(g) + AlF63-

(aq) + AlF4- + 4e or

3O2-(aq) + 3/2 C 3/2 CO2(g) + 6e

BAUXITE ALUMINA ALUMINIUM


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Et2O

Based on the reaction above, all of reaction can write by simpler reaction

became:

2Al2O3(s) + 3C(s) 4Al(s) + 3 CO2(g) (Kirna;2002)

Uses

Aluminium foils are able to withstand the heat, because it has powerreflectivity of 95%-98% that receivedsolar heat will be reflected back.

Installationof aluminium foil placed under the battens, so the heat received

by a layer of roofing directly returned from getting into the room.

Aluminium foil is heat resistant of roof coating, roof insulation serves as a

building material made of strong, elasticand waterproofasa weelas

freonresistant. So,it is safe for environment.

Because of aluminium is very light, so it can be used in the transportationsindustry such as airplane. Aluminium has a weight1/3 if compare with iron

or steel.

Resources:Copyright from Paper of Aluminium BY Brawijaya students, 2009

Hydrides and related complexes

AlH3 is a colorless in volatile solid which is extensively polymerized via

Al-H-Al bonds, it is thermally unstable above 150-200, is a strong reducing agent

and reacts violently with water other protic reagents to liberate H2. Several

crystalline and amorphous modifications have been described and the structure of-AlH3 has been determined by X-ray and neutron diffraction. AlH3 is prepared

by the reaction of ethereal solutions of LiAlH4 and AlCl3 under very carefully

controlled condition (Greenwood:1997).

3LiAlH4 + AlCl3 4[AlH3(Et2O)6] + 3LiCl

AlH3 readily forms adducts with strong Lewis bases (L) but these are more

conveniently prepared by reactions of the type


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LiAlH4 + NMe3HCl [AlH3(NMe3)] + LiCl + H2

[AlH3(NMe3)] has a tetrahedral structure and can take up a further mole of ligand

to give [AlH3(NMe3)2] this was the first compound in which Al was shown to

adopt a 5-coordinate trigonal bipyramidal structure. LiAlH4 is a white crystalline

solid, stable is dry air but highly reactive towards moisture, protic solvents, and

many organic functional groups. It is readily soluble in ether and is normally used

in this solvent. LiAlH4 has proved to be an outstandingly versatile reducing agent

since its discovery some 50 years ago. It can be prepared on the laboratory (and

industrial) scale by the reaction

4LiH + AlCl3 LiAlH4 + 3LiCl

On the industrial (multitonne) scale it can also be prepared by direct high-pressure

reaction of the elements or preferably via the intermediate formation of the Na

analogue.

Na + Al + 2H2 NaAlH4

Halides and their Complexes

AlF3 is made by treating AL2O3 with HF gas at 700o and the other

trihalides are made by the direct exothermic combination of element. AlF3 is

important in the industrial production. AlF3 is also prepared by the reaction :

Al2O3 + 6HF 2AlF3 + 3H2O

AlCl3 find extensive use as a Friedel-Crafts catalyst (p.236). AlF3 is

differs from the other trihalides of Al in being involatile and insoluble, and in

having a much greater heat of formation. In AlF3 each Al is surrounded by a

distorted octahedron of 6 F atoms and the 1:3 stoichiometry is achieved by the

corner sharing of each F between 2 octahedral.

Properties of Crystalline AlX3

Properties AlF3 AlCl3 AlBr3 AlI3

MP/ C 1290 192.4 97.8 189.4

Sublimation 1272 180 256 382

H0f 1498 707 527 310

Et2O


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Aluminium chloride is used as an acid catalyst, as a chemical intermediate for

other aluminium compounds, in the cracking of petroleum in the manufacturing of

rubbers and lubricants, and as an antiperspirant. The hexahydrate form is used in

preserving wood, in disinfecting stables and slaughterhouses, in deodorants and

antiperspirants, in cosmetics as a topical astringent, in refining crude oil, in dyeing

fabrics, and in manufacturing paper (Knottnerus:2009)

By contrast, Al2Br6 and Al2I6 form dimeric molecular units in the

crystalline phase as well as in the liquid and gaseous states and fusion is not

attended by such extensive changes in properties . In the gas phase Hdissoc is

59KJ mol-1 for AlBr3 and 50 kJ mol-1 for AlI3. The preparation to get Al2Br6 and

Al2I6,by the reaction:

2Al(s) + 3Br2(l) Al2Br6(s)

2Al(s) + 3I2(l) Al2I6(s)

Br

Br

Al Al

Br

Br

Br

Br

I

I

Al Al

I

I

I

I

The structure of Al2Br6 The structure of Al2I6

Aluminum chloride is a Lewis acid is most commonly used. The

application is used in the chemical industry, as catalysts of Friedel-Crafts

reactions, both as akilasy and alkylation, for example for the preparation of

antraquinone (dye industry) from benzene and phosgene. The product that

produce include detergents and etilbenzen. This substance is also used in

polymerization and isomerization reactions of hydrocarbons.(Knottnerus:2009)

Carbides and nitrides

The chemical formula of aluminium carbide is Al4C3. It has the

appearance of pale yellow to brown crystals. It is stable up to 1400 C and

decomposes in water with the production of methane. Aluminium carbide has an

unusual crystal structure that consists of two types of layers. It is based on AlC4

tetrahedral of two types and thus two types of carbon atoms. One is surrounded by
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a deformed octahedron of 6 Al atoms at a distance of 217 pm. The other is

surrounded by 4 Al atoms at 190194 pm and a fifth Al atom at 221 pm.

Aluminium carbide hydrolyses with evolution of methane. The reaction

proceeds at room temperature but is rapidly accelerated by heating.

Al4C3 + 12 H2O 4 Al(OH)3 + 3 CH4

Similar reactions occur with other protic reagents:

Al4C3 + 12 HCl 4 AlCl3 + 3 CH4

Aluminium carbide is prepared by direct reaction of aluminium and carbon in an

electric arc furnace 4 Al + 3 C Al4C3

An alternative reaction begins with alumina, but it is less favorable because ofgeneration ofcarbon monoxide. The reaction as follow:

2 Al2O3 + 9 C Al4C3 + 6 CO

Silicon carbide also reacts with aluminium to yield Al4C3. This conversion limits

the mechanical applications of SiC, because Al4C3 is more brittle than SiC

4 Al + 3 SiC Al4C3 + 3 Si

Aluminium carbide particles finely dispersed in aluminium matrix lower the

tendency of the material to creep, especially in combination with silicon carbide

particles. Aluminium carbide can be used as an abrasive in high-speed cutting

tools

Aluminium Nitride is the only stable compound in the binary system Al -

N and exists in only one crystal structure (wurtzite, hexagonal). Pure AlN has a

density of 3.26 g/cm3 and dissociates under atmospheric pressure above 2500

C. Pure AlN is colorless and translucent but is easily colored by dopants or

impurities. Thus, carbon impurities cause the typical light gray color of AlN

powder. AlN powder is susceptible to hydrolysis by water and humidity. This is

the reason for its characteristic ammonia smell. Because AlN is a covalent

compound, limited atomic mobility prevents complete densification of pure AlN.

Thus, relatively high pressures or sintering aids are required to assist

densification. Typical sintering additives are rare-earth or alkaline-earth oxides.

To achieve high thermal conductivities mostly yttrium compounds are used. The

formation and microstructural distribution of yttrium aluminium garnet controls
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both densification and thermal properties. The sintering temperatures highly

depend on the additives and range from 1600 to 1900 C.

In summary aluminium nitride components and substrates are used momentarily

for various applications:

Power electronics (electrical engines)

Micro electronics (LSI circuits, sensor carriers, high frequency

modules)

Naval radio systems, defense systems

Railway systems (inverters for drive systems)

Environmental systems (emission control)

AlN is synthesized by the carbothermal reduction ofaluminium oxide or by direct

nitridation of aluminium. The use ofsintering aids and hot pressing is required to

produce a dense technical grade material. (Davydson,2009)

Oxides

Alumina (Al2O3) or Aluminum Oxide is the only oxide formed by the

metal aluminum and occurs in nature as the minerals corundum (Al2O3);

diaspore, gibbsite and most commonly as bauxite, which is an impure form of

gibbsite. The precious stones ruby andsapphire are composed of corundum (and

thus also natural forms of alumina) getting their colors by small amounts of

impurities. Some of these are Corundum (discovered in 1799), Diaspore (1801),

Gibbsite (1820), Boehmite (1924), Bayerite (1925), Nordstrandite (1956).

Alumina is main materials in process of aluminium electrolyze, aluminium

have morphology as white powder with melt point 2050 C and gravity

specification is 3,5-4,0. Alumina is usually in the form of ionic crystals, but theoxide ion (O2-) polarized by aluminum ions so that most bonds are covalent, melts

at a temperature of 2053C, insoluble in water is very hard and stable. Aluminum

oxide is found in nature as corundum as an extremely hard crystal that is used as

an abrasive and sharpening. Corundum containing impurities (a little mix of other

metal oxides) are widely used as precious stones such as:

White sapphire Jewel (no mixing) Blue sapphire jewel (containing Fe, Ti)
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properties. In case of fire the heat energy is absorbed by the aluminum oxide

trihydrate this.

The preparation alumina from bauxite by bayer process:

1. Hulling process of bauxite until certain size2. The dissolve process of alumina with NaOH by concentration of 35-45%.

Al2O3.2H2O + 2 NaOH 2 Na2AlO2 + 3H2O

3. Separation of soiled that precipitate by filter and get the colorless sodiumaluminate solution

4. Sodium aluminate dissolve in water and then the precipitate of sodiumaluminate by adding seed (smooth powder of alumina) which spread in

alumina solution and precipitation of alumina, so that obtained

precipitation of alumina with big size as result of production of alumina

and the smooth of precipitation of alumina used as seed to precipitation.

2NaAlO2 + 4H2O 2 NaOH + Al2O3.3H2O

5. Then, alumina precipitation toasted to vapor the water6. Dry of aluminium to fusion aluminium materials.

Thhere are some uses of alumina such as:

Mechanical Cheramics:

Due to their excellent mechanical properties, alumina based ceramics are being

increasingly used as a substitute material for several applications. These include

the use of ceramic for abrasive and cutting tools. Alumina-based ceramics are also

used for making extrusion and sanding nozzles and for parts of machinery

(particularly in the mining industry) where wear resistant qualities are critical.

They are also used for making ice skate blades and some friction parts such as

wear-resistant seals in piston engines. (Ibid. Mechanical Ceramics)Military Uses

The shock-resisting quality of alumina-ceramics makes them useful as armor

plating for protection of tanks and helicopters as well as for bullet-proof jackets

and in aeronautics for protection of hydraulic parts.

Bio Medical

Alumina is also an inert substance, and at room temperature, it is insoluble

in all ordinary chemical reagents. It also has excellent wear resistance and can be


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polished to high surface finish. These qualities make it useful as a biomaterial. For

example, alumina is used for artificial joint replacements; porous alumina is used

as a bone spacer and for teeth implants. (Alumina as a bio material) In the

biomedical field, alumina is also used for cochlear implants (hearing aids for the

deaf). In the more general field of medical instruments, ceramics are also used to

manufacture medical tubes and other scientific, medical products

Electronics.

Alumina is widely used in the electronics industry for passive components such as

interconnection, resistances, and capacitors and is specifically employed in

applications such as substrates for hybrid circuits, multi-layer interconnection

circuits, materials for type II condensers, and hyper frequency resonators (mobile

phones).

Chalcogenides

The chalcogens are the chemical elements in group VIA of the periodic

table. This group is also known as the oxygen family. It consists of the elements

oxygen (O), sulfur (S), selenium (Se), tellurium (Te), the radioactive element

polonium (Po). The synthetic element livermorium (Lv) is predicted to be a

chalcogen as well. The word chalcogen comes from the Greek word chalkos,

meaning "bronze" or "ore", and the wordgens, meaning "born". While sulfur has

been known since antiquity, oxygen was only recognized as an element in the

18th century. Selenium, tellurium and polonium were discovered in the 19th

century, while livermorium was discovered in 2000.

At normal temperatures the only stable chalconides of Al are Al2S3

(white), Al2Se3 (grey) and Al2Te3 (dark grey). It can be prepared by direct reaction

of the elements at 1000 and all hydrolyze rapidly and completely in aqueous

solution to give Al(OH)3 and H2X (X=S, Se, Te). The small size of Al relative to

the chalcogens dictates tetrahedral coordination and the various polymorphs are

related to wurtzite (hexagonal ZnS), two-thirds of the available metal sites being

occupied in either an ordered () or a random () fashion. Al2S3 also has a -form
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related to -Al2O3, and very recently a novel high-temperature hexagonal

modification of Al2S3 containing 5-coordinate Al has been obtained by annealing

-Al2O3 at 550 C; in this new formhalf the Al atoms are tetrahedrally

coodinated (Al-S 223-227 pm) whereas the other half are in trigonal bipyramidal

coodination with Al-Seq 227-232 pm and Al-Sax 250-252 pm. Aluminium sulfide

is readily prepared by ignition of the elements.

2 Al + 3 S Al2S3

This reaction is extremely exothermic and it is not necessary or desirable to heat

the whole mass of the sulfur-aluminium mixture; (except possibly for very small

amounts of reactants). The product will be created in a fused form it reaches a

temperature greater than 1100 C and may melt its way through steel. The cooled

product is very hard.

Resources: Copyright from wikipedia

Hydroxides

Aluminium hydroxide is called hydrate of alumina. It is found in nature as

the mineral. Closely related of aluminium oxide hydroxide, AlO(OH), and

aluminium oxide. These compounds together are the major components of the

aluminium ore bauxite. Freshly precipitated aluminium hydroxide forms gels,

which is the basis for application of aluminium salts as flocculants in water

purification. This gel crystallizes with time. Aluminium hydroxide gels can be to

form an amorphous aluminium hydroxide powder, which is readily soluble in

acids.

Diaspore, -AlO(OH) occurs in some types of clay and bauxite; it is

stable in the range 280-450 and can be mde by hydrothermal treatment of

bochmite, -AlO(OH), in 0.4% aqueous NaOH at 380 and 500 atm. Crystalline

boechmite is readily prepared by warming the amorphous, gelatinous white
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precipitate which first forms when aqueous NH3 is added to cold solutions of Al

salts. In -AlO(OH) the O atoms are arranged in hcp; continous chains of edge-

shared octahedral are stacked in layers and are further interconnected by H bonds.

The underlying hcp structure ensures that diaspore dehydrates directly to -Al2O3

(corundum) which has the same basic hcp arrangement of o atoms. The structure

is also adopted by several other-MO(OH) (M=Ba, V, Mn, and Fe); this contrast

with the structure of boechmite, -AlO(OH), which as a whole is not close-

packed, though within each layer the O atoms are arranged in cubic close packing.

dehydration at temperatures up to 450 proceeds via a succession of phases to the

cubic -Al2O3 and the (hexagonal) strucutre cannot be attained without much

more reconstruction of the lattice at 1100-1200 (Greenwood:1997).

Aluminium hydroxide is used in stomach antacids, as a desiccant powder

in antiperspirants and dentifrices, in packaging materials, as a chemical

intermediate, as a filler in plastics, rubber, cosmetics and paper, as a soft abrasive

for brass and plastics, as a glass additive to

increase mechanical strength and resistance to thermal shock, weathering, and

chemicals, and in ceramics. Aluminium hydroxide is also used pharmaceutically

to lower the plasma phosphorus levels of patients with renal failure.

Spinel

Magnesium aluminium is the large member of the spinnel group minerals.

It has the formula MgAl2O4. Spinel crystallizes in the isometric system commonly

in the form of crystal octahedral. It has an imperfect octahedral cleavage and a

conchoidal fracture. Its hardness is 8, its specific gravity is 3.5-4.1 and it is

transparent to opaque with a vitreous to dull luster. It may be colorless, but is

usually various shades ofred, blue, green, yellow, brown orblack.

Resources: Copyright Rob Lavinsky & irocks.com
http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardnesshttp://en.wikipedia.org/wiki/Specific_gravityhttp://en.wikipedia.org/wiki/Redhttp://en.wikipedia.org/wiki/Bluehttp://en.wikipedia.org/wiki/Greenhttp://en.wikipedia.org/wiki/Yellowhttp://en.wikipedia.org/wiki/Brownhttp://en.wikipedia.org/wiki/Blackhttp://www.mindat.org/click.php?enc=aHR0cDovL3d3dy5pcm9ja3MuY29tLw%3D%3Dhttp://www.mindat.org/click.php?enc=aHR0cDovL3d3dy5pcm9ja3MuY29tLw%3D%3Dhttp://www.mindat.org/click.php?enc=aHR0cDovL3d3dy5pcm9ja3MuY29tLw%3D%3Dhttp://www.mindat.org/click.php?enc=aHR0cDovL3d3dy5pcm9ja3MuY29tLw%3D%3Dhttp://en.wikipedia.org/wiki/Blackhttp://en.wikipedia.org/wiki/Brownhttp://en.wikipedia.org/wiki/Yellowhttp://en.wikipedia.org/wiki/Greenhttp://en.wikipedia.org/wiki/Bluehttp://en.wikipedia.org/wiki/Redhttp://en.wikipedia.org/wiki/Specific_gravityhttp://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness


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Salt of oxyacids

Aluminium Sulfate is an aluminium oxy-acid salt that is extremely soluble

in water. An anhydrous form exists but it is relatively unimportant. Aluminium

sulfate (Al2(SO4)3), commonly called alum, is produced as white crystals which

are non-combustible and soluble in water. This dry hydrate (Al2(SO4)3.14H2O) is

17% Al2O3 and is also sold as a 47% aluminium sulfate solution which is 8%

Al2O3. It is also sold in solid form as kibbled, ground or dust. Aluminium sulfate

has been used by man since 2000 BC, when the Egyptians used a mineral alum as

a mordant in dyeing. It has long been used in paper sizing to improve durability

and ink receptivity and in water treatment to clarify water. Other uses for alum

include wastewater treatment, as a waterproofing agent and accelerator in

concrete, as a clarifier for fats and oils and as a foaming agent in fire foams. In

paper making the alum reacts with rosin sizes of various types, helping to attach

the newly formed rosin aluminates to fibres. Sizing makes the paper water

resistant. Alum, which exhibits a cationic charge, is also used to flocculate anionic

trash including paper fines and other anionically charged material by

neutralization, in a similar way to water treatment, improving drainage, retention

and strength of the material. Aluminium sulfate is produced according to the

following exothermic reaction: 2Al(OH)3 + 3H2SO4 + 8H2O Al2(SO4)3 .14H2O

fH = -156 kJ mol-1 Alum is generally produced batch wise in a reactor. The

reactor is a stirred vessel made of materials resistant to the acidity and heat of the

reaction.(Mathers,2006).

Resources:Copyright from Wikipedia


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Based o the explanation above, aluminium is the most abundant metal in

the earth crust (8.3% by weight), it is exceeded in abundance only by O (45.5%)

and Si (25.7%) and is approached only by Fe (6.2%) and Ca (4.6%). Aluminium

was obtained by Humpry Davy followed by Oersted in 1825, Deviller and Wohler

in 1827 and have important roles in industry, pharmacy, chemistry, electronic, etc.

Aluminium have physical and chemical properties that make aluminium is

uniqueness metal. There are two process isolation of aluminium such as by Bayer

and Hall-Heroult Processes. Aluminium has several compounds such as Hydrides

and their complexes include of AlH3. Carbides and nitrides include of Al4C3 and

AlN. Halides and their complexes of aluminium included of AlF3, AlCl3,AlI3, and

its dimmers. Oxide of aluminium is Al2O3 that called alumina. Chacogenides of

aluminium is the compound that bond with oxygen group . the most stable

chalcogenides of aluminium are Al2S3, Al2se3, and Al2Te3. The hydroxides of

aluminium is called called hydrate of alumina that has formula AlO(OH). Spinel

of aluminium is magnesium aluminate that has chemical formula of MgAl2O4.

Spinnel can be obtained in minerals in the form of rocks that has several colors

and the salt of oxyacid is aluminium sulfate in white crystal.


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REFFERENCES

Cotton, F.Albert. Wilkinson, Geoffrey.Gaus, Paul 1995. Basic Inorganic

Chemistry Third Edition . London: Joh Willey & Sons INC.

Greenwood. 1997. Chemistry of the Elements. London: Elsevier

Mathers,Gene. 2002. The Welding of Aluminium and Its Alloys. New York :

WoodHead

Kirna, Made. Suardana. 2002. Buku Penuntun Belajar Kimia Anorganik II.

Singaraja: Iniversitas Pendidikan Ganesha.

Knottnerus,J. 2009. Aluminium and aluminium compounds. Netherlands:

Gezondheidsraad Voorzitter

Enhag,P. 2004.Encyclopedia of The Elements. Sweden:Wiley VCH

Davydson.2009.All About Aluminium.accessed on February 17th 2013 from

http://sam.davyson.com/as/physics/aluminium/site/uses

Anonymous,2009, BAYER PROCESS CHEMISTRY, accessed on February 17th

2013,from

http://www.worldaluminium.org/About+Aluminium//nternational Aluminium

Institute.htm,

Anonymous.2009.The Properties and Uses of Aluminium.accessed on February

17th 2013 from

http://www.aluminiumleader.com/en/facts/history.pdf

http:www.wikipedia.com
http://sam.davyson.com/as/physics/aluminium/site/useshttp://sam.davyson.com/as/physics/aluminium/site/useshttp://www.aluminiumleader.com/en/facts/history.pdfhttp://www.aluminiumleader.com/en/facts/history.pdfhttp://www.aluminiumleader.com/en/facts/history.pdfhttp://sam.davyson.com/as/physics/aluminium/site/uses

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