Oxoacids of phosphorus

Phosphorus forms a number of oxoacids. They are hypophosphorous acid (H3PO2), Phosphorous acid (H3PO3), Hypophosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7) and meta phosphoric acid (HPO2)n.

1. Hypo phosphorous acid (H3PO2) or phosphinic acid

It is preapred by the oxidation of phosphine by iodine in the presence of calculated amount of water. It is a monobasic acid.

PH3 + 2I2 + 2H2O -----------> H3PO2 + 4 HI



2. Phosphorous acid (H3PO3) or phosphonic acid

It is prepared by hydrolysis of phosphorous trioxide (P4O6). Phosphorous acid is dibasic.
P4O6 + 6H2O ----------> 4H3PO3





3. Hypophosphoric acid (H4P2O6)

It is prepared by controlled oxidation of red phosphorous with sodium chlorite solution, when disodium salt of hypophosphoric acid is formed which then passing through cation exchanger yield hypophosphoric acid. Hypophosphoric acid is tetrabasic.
2P + 2NaClO2 + 2H2O ---------> Na2H2P2O6 + 2HCl
Na2H2P2O6 + 2H -----resin-----> H4P2O6 + 2Na - resin





4. Orthophosphoric acid (H3PO4)

It is prepared by treating P4O10 with boiled water. It is a tri basic acid.

P4O10 + 6H2O ----------> 4H3PO4





5. Pyrophosphoric acid (H4p2O7)

It is prepared by heating orthophosphonic acid about 250oc. It is a tetrabasic acid.

2H3PO4 ---------> H4P2O7 + H2O





6. Meta phosphoric (HPO3)n.

It is obtained by heating orthophosphoric acid to about 850 K. Metaphosphoric acid does not exist as monomer. It exist as cyclic trimer, cyclic tetramer or polymer.

H3PO4 -------------> HPO3 + H2O


Related articles

Oxides Of Phosphorus

Phosphine gas

Mechanism of Micelle Formation

Definition of Micelles (Associated colloids)

There are some substances which at low concentrations behave as normal strong electrolytes but at higher concentrations exhibit colloidal behavior due to the formation of aggregated particles. These associated particles are called micelles or associated colloids. The formation of micelles take place only above a particular temperature called Kraft temperature (T_K) and above a particular concentration called critical micelle concentration (CMC).
Example: Detergents and soaps.



Soap is sodium salt of higher fatty acid like C₁₇H₃₅COONa (sodium stearate). In aqueous solution soap ionizes as The RCOO^- ions (C₁₇H₃₅COO^-) and Na⁺ ions.

C₁₇H₃₅COONa ---------> C₁₇H₃₅COO^- + Na⁺

The RCOO^- ions however consist of two parts. That is, long hydrocarbon chain R(-C₁₇H₃₅) also called non-polar tail which is hydrophobic and the polar group COO^- called polar-ionic head which is hydrophilic. In concentrated solution, these stearate ions get aggregated to form colloidal solution or micelles. For soaps the critical micelle concentration (CMC) is 10^-4 to 10^-3 mol Lsup>-


Related chemistry article Lyophilic colloids and lyophobic colloids

Lyophilic colloids and lyophobic colloids

Depending upon the nature of interaction between the dispersed phase and the dispersion medium, colloids are classified in to the lyophilic colloids (solvent attracting) and lyophobic colloids (solvent repelling). If water is the dispersion medium, it is called as hydrophilic and hydrophobic colloid respectively.

Lyophilic colloids

The meaning of the word 'lyophilic' is 'liquid-loving' or 'solvent attracting'. That means, these are colloids in which there is strong interaction between the two phases. Lyophilic colloids are those dispersions in which the dispersed phase exhibits a definite affinity for the medium and as a results extensive solvation of the colloidal particles takes place. They are directly formed by mixing the two phases.Eg :- Gum, soap, starch, gelatin, rubber etc.
These sols are also called reversible sols. Because, if the dispersion medium is separated from the dispersed phase, the sol can be reconstituted by simply mixing with the dispersion medium.

Lyophobic colloids

The word 'lyophobic' means 'liquid hating', ie, in these sols there is little or no interaction between the two phases. Lyophobic sols are those dispersions in which there is very little attraction between dispersed phase and dispersion medium, They cannot be prepared by simply mixing the two phases. Eg :- Dispersion of metals in water, colloidal hydroxides etc.
They are irreversible in nature. Because, once precipitated, they do not given back the colloidal sol by simple addition of the dispersion medium.

Comparison between lyophilic and lyophobic

Lyophilic colloidal particles are easily solvated. Lyophobic colloidal particles are weakly solvated. Small quantities of electrolytes have little effect but large amount may cause salting out in lyophilic sol. In Lyophobic sol small quantities of electrolytes causes precipitation. The particles cannot be readily detected in the ultra microscope in lyophilic sol. The particles are easily detected in the ultra microscope in Lyophobic sol. Particles may migrate in either direction or not at all in an electric field in lyophilic sol. In lyophobic sol particles migrate in only one direction in an electric field. In lyophilic sol surface tension is generally lower than that of dispersion medium. In lyophobic sol surface tension is almost similar to that of the dispersion medium. Lyophilic sols are reversible. Lyophobic sols are irreversible.

Electrochemical Theory of Rusting

Corrosion Of Iron

Corrosion is the process in which a metal is destructed as a result of its reaction with environment. Corrosion of iron is known as rusting. Rusting is the hydrated ferric oxide. Other examples for corrosion are tarnishing of silver and development of green coating on copper and bronze. In corrosion metals undergo anodic oxidation to metal oxides.

Electrochemical theory of rusting

The rusting of iron is an electrochemical process involving the following steps.

The moister containing CO2 acts as electrolyte.

H₂O + CO₂ ------> H₂CO₃
H₂CO₃ ------> 2H+ + CO₃^2-

The iron is oxidized by the removal of electrons and acts as the anode.

Fe ------> Fe²⁺ + 2electron

The H+ ions from the electrolyte accept electrons from the adjacent areas on metal surface and function as cathode.

4H⁺ + 4electron ------> 2H₂

The atmospheric oxygen moves hydrogen as water.

2H₂ + O₂ ------> 2H₂O

Adding the above two equations,

4H+ +O₂ + 4electron ------> 2H₂O


Fe²⁺ formed at the anode is further oxidized to Fe³⁺ by atmospheric oxygen in presence of moisture.

4Fe²⁺ + O₂ + 4H₂O ------> 2Fe₂O₃ + 8H⁺

The ferric oxide gets hydrated to form rust.

Fe2₂O₃ + xH₂O ------> Fe₂O₃.xH₂O (rust)

Rust is chemically hydrated iron oxide (Fe₂O₃.xH₂O). It does not stick to the surface of iron. Hence fresh surface of iron is always exposed and undergo further rusting. Corrosion causes several damages to buildings, bridges, ships and other objects made of metals. Some of the important methods used to prevent corrosion of metals are barrier protection, Sacrificial protection, Electrical protection, using anti rust solution.

Prevention of Corrosion Methods

1. Barrier protection

In this method a barrier is placed between metal and atmosphere. This is actually done by coating the metals surface with paint oil or grease. The barrier avoids the direct contact of the metal surface with the environment and hence prevents corrosion.

2. Sacrificial Protection

In this method the iron object is covered with a thin coating of metal like zinc which is more reactive than iron. Here the active metal which is coated will act as anode and undergo oxidation in preference to iron. The process of coating iron objects with zinc is called galvanization.

3. Electrical Protection or Cathodic Protection

In this method, the iron object which is to be protected from corrosion is made cathode by coupling it with another more active metal. Here the active metal acts as anode and protect the iron article from destruction. The iron object will remain protected as long as the active metal in present.

4. Using anti rust Solution

Alkaline phosphate and alkaline chromates are used as anti rust solutions. When anti rust solution are applied on iron objects, the iron phosphate or iron chromate formed are act as insoluble and heat resistant coating and prevent rusting.

Prepration of phenol

Preparation of phenol from benzene derivatives

Phenol was first isolated in the early nineteenth century from coal tar. Nowadays, phenol is commercially produced synthetically. In the laboratory, phenols may be prepared from benzene derivatives by any of the following methods.

1. From sodium benzene sulphonate

Benezene sulphonic acid when treated with NaOH gives its sodium salt. Sodium benzene sulphonate. This when fused with NaOH at temperature between 570-620 K, gives sodium phenoxide, which on hydrolysis with dilute mineral acid gives phenol.

2. From Benzene diazonium chloride

Benzene diazonium chloride is formed by treating aniline with nitrous acid (NANO2 + HCl) at 273-283 K temperature. On warming an aqueous solution of benzene diazonium chloride, it is hydrolysed to form phenol.





3. From Chlorobenzene (Dow’s process)

Chlorobenzene on heating with 10% aqueous solution of NaOH at about 623K under 200 atmospheric pressure in the presence of copper salt catalyst, sodium phenoxide is formed. This on acidification with dilute HCl undergoes hydrolysis to give phenol. The method is called Dow’s process.

For industrial preparation of Phenol Visit http://entrancechemistry.blogspot.in/2012/07/industrial-preparation-of-phenol.html

Related post Chemical properties of Alcohols and Phenols

Industrial Preparation of Phenol

Preparation of Phenol From Coal Tar

Phenol is commercially prepared from the middle oil fraction (443-503K) of coal tar distillate in which it occurs with cresols and naphthalene. First naphthalene is removed by chilling the fraction. The remaining oil is now treated with H₂SO₄ to remove basic impurities and phenol is then extracted with dilute caustic soda. The aqueous layer is separated and phenol is precipitated with H₂SO₄ or CO₂. It is finally purified by distillation.

Preparation of Phenol From Cumene

Nowadays, phenol is manufactured from the hydrocarbon cumene. Cumene (isopropyl benzene) is first prepared from benzene and propene by Friedel-Crafts reaction in presence of phosphoric acid of aluminum oxide. Cumene is oxidized in presence of air to cumene hydroperoxide, which is then converted to phenol and acetone by treating it with dilute acid. Acetone, a byproduct of this reaction, is also obtained in large quantity by this method.

Phenol has a melting point of 314 K and it is moderately soluble in water (8% at 298K).

Uses of Phenol

Phenol is a strong antiseptic. It is widely used as a raw material for the manufacture of important dyes, drugs and pharmaceuticals, polymers like Bakelite a and a number of organic chemicals like salicylic acid, picric acid, phenolphthalein etc.

For preparation of Phenol by chemical method visit Prepration of phenol

Reaction of Ether with Hydrogen Iodide (HI)

Chemical properties of Ethers (With HI)

On heating with concentrated Hydrogen iodide (HI) the C-O bond in ethers breaks forming alcohol and alkyl iodide. For example,

C₂H₅ -O-C₂H₅ + HI ------------> C₂H₅ - I + C₂H₅OH

On boiling with excess of concentrated Hydrogen iodide (HI), Alkyl iodide is formed.


C₂H₅ -O-C₂H₅ + 2HI ------------> 2C₂H₅I + H₂O

In the case of mixed ethers with two different alkyl groups, the site of cleavage and hence the alcohol and alkyl iodide that form depend on the nature of the alkyl groups.

When one group is methyl and the other is primary or secondary alkyl group, it is the lower alkyl group that forms alkyl iodide due to steric factors.
For Example,









When one group is methyl and the other alkyl group is a tertiary group, the halide formed is a tertiary group, the halide formed is a tertiary halide.
For Example,






It is because the attack by I- takes place at that carbon of alkyl group, which has a greater electron pushing inductive effect and a lower electron density.

Phenolic ethers react with HI to form phenol and alkyl iodide. This can be attributed to the resonance and steric effects of the benzene ring.


For more about chemical reaction of ether visit http://entrancechemistry.blogspot.in/2012/07/chemical-properties-of-ether.html

Manufacture of Ethanol from Molasses

Preparation of Ethanol (Drinking Alcohol)

Ethanol is the most important member of the alcohol series. Ethanol is prepared industrially by the fermentation of sugars in molasses, sugarcane or fruits such as grapes or starch obtained from various grains. Fermentation is the oldest method of making ethanol from sugars. It is the slow decomposition of complex organic compounds into simple compounds by the action of biological catalysts called enzymes.

Manufacture of Ethanol from Molasses

Molasses is the mother liquor left behind after the crystallization of sugar from sugarcane juice. It contains about 40% non-crystallizable sugar.
Mollasses is first diluted to about 10% concentration of sugar. Then, calculated amount of yeast is added and kept at an optimum temperature of about 305K. Yeast provides the enzymes invertase and Zymase which can cause fermentation. The enzyme invertase catalyses the hydrolysis of sugar into glucose and fructose. Glucose and fructose are decomposed into ethanol in the presence of the enzyme zymase. Ultimately, a dilute solution of ethanol (8-10%), called 'wash' is obtained.

Chemical Equations

C₁₂H₂₂O₁₁ + H₂O ------invertase------> C₆H₁₂O₆ (glucose) + C₆H₁₂O₆ (fructose)


C₆H₁₂O₆ (glucose / fructose) -----zymase-----> 2C₂H₅ - OH (ethanol) + 2CO₂

Preparation of Methanol

Industrial Preparation of Methanol

Methanol, CH₃OH, which is also known as 'Wood alcohol' or 'Wood spirit'. Methanol is produced by the destructive distillation of wood. Today, most of the methanol is produced by catalytic hydrogenation of carbon monoxide at high pressure and temperature and in presence of Cu-ZnO-Cr₂O₃ catalyst.

Co + 2H₂ ----(Cu-ZnO-Cr₂O₃, 200-300 atm, 573-673 K)------> CH₃OH

Methanol is a colourless liquid with boiling point 337 K. It is highly poisonous in nature. Injection of even small quantities of methanol can cause blindness and in large quantities, even death.

Uses of Methanol

Methanol is used as a solvent on paints, varnishes etc. and methanol is chiefly for the preparation of formaldehyde. Methanol is also used for denaturing ethanol.

For more visit Preparation of alcohol

Ether forming Peroxides (Auto oxidation)

Reaction of ethers with atmospheric Oxygen

Ethers form peroxides by the action of atmospheric oxygen or ozonised oxygen due to co-ordination of one lone pair of the ethereal oxygen with another oxygen atom

For example,

C₂H₅O₂H₅ + O ------------> (C₂H₅)₂O (diethyl ether Peroxide)---> O


These peroxides are unstable compounds and decomposes violently on heating. Hence, ethers should never be evaporated to dryness. it is essential to remove the peroxides by washing before distilling the ether. This can be done by washing the ether with a solution of ferrous sulphate.


For Chemical properties of ethers visit http://entrancechemistry.blogspot.com/2012/07/chemical-properties-of-ether.html

Reaction of Ether with Sulphuric Acid

Chemical Properties of Ethers (with H₂SO₄)

On heating with dilute sulfuric acid under pressure, ethers are hydrolysed to alcohols.
For example,

C₂H₅OC₂H₅ + H₂O ----(dil.H2so4,high pressure)-----> 2C₂H₅OH

Mixed ethers under similar conditions give a mixture of alcohols.

CH₃OC₂H₅ + H₂O ------(dil.H2so4,high pressure)------>C₂H₅OH + CH₃OH

But if concentrated sulfuric acid is used, then the products are alcohol and alkyl hydrogen sulphate.

C₂H₅OC₂H₅ (Diethyl ether) -----(heat, conc. H2SO4)-----> C₂H₅OH (ethanol)+ C₂H₅OSO₂OH (ethyl hydrogen sulphate)


Ethers containing secondary and tertiary alkyl groups form alkenes with conc. sulphuric acid.
For example




For more about chemical reaction of ether visit http://entrancechemistry.blogspot.in/2012/07/chemical-properties-of-ether.html

Chemical Properties of Ether

The functional group in ethers (-O-) is comparatively inert with respect to the -OH functional group in alcohols and phenols even though the oxygen atom in each of the groups has two lone pairs of electrones. Therefore, ethers are not easily attacked by alkalies, dilute mineral acids, PCl₅, metallic sodium etc. under ordinary conditions. But they undergo chemical reactions under specific conditions.

1. Cleavage of C-O bond in ethers

The cleavage of C-O bond in ethers takes palce under drastic conditions with excess of hydrogen halides. The reaction of dialkyl ether gives two alkyl halide molecules.

R-O-R + 2HX -------------> 2RX + H₂O

Alkyl aryl ethers are cleaved at the alkyl-oxygen bond. The reaction yields phenol and alkyl halide.

Ethers with two different alkyl groups are also cleaved in the same manner.

R-O-R' + H-X ------------> R-X + R'-OH

The order of reactivity of hydrogen halides is as follows: HI > HBr > HCl.

1. Reaction with HI

2. Reaction with H₂SO₄

3. Formation of Peroxides

Chemical properties of Group 16 elements

Trends in chemical reactivity of group 16 elements

1. The metallic character increases as we descend the group. Oxygen and sulphur are typical nonmetals. Selenium (Se) and Te are metalloids and are semiconductors. Polonium is a metal.

2. Tendency to form multiple bond decreases down the group.
Example O=C=O is stable, S=C=C is moderately stable, Se=C=Se decomposes readily and Te=C=Te is not formed.

3. Formation of Hydrides

All the elements of group 16 form hydrides of the type H₂M (where M=O,S,Se,Te or Po). The stability of hydrides decreases as we go down the group. Except H₂O, all other hydrides are poisonous foul smelling gases. Their acidic character and reducing nature increases down the group. All these hydrides have angular structure and the central atom is in sp³ hybridisation.

4. Formation of Halides
Element of group 16 form a large number of halides. The compounds of oxygen with fluorine are called oxyfluorides because fluorine is more electronegative than oxygen (example OF₂).

The main types of halides are
1. Monohalides of the type M₂X₂
2. Dihalides of the type MX₂
3. Tetrahalides of the type MX₄
4. Hexahalides of the type MX₆

5. Formation Of Oxides
Group 16 elements mainly form three types of oxides.
1. Monoxides: Except Selenium (Se), all other elements of the group form monoxides of the type MO (Example SO)

2. Dioxides: All the elements of group 16 form dioxides of the type MO₂ (Example SO₂)

3. Trioxides: All the elements of the group form trioxides of the type MO₃

Physical Properties Of Ethers

Lower members of ethers are gases while higher members are volatile with pleasant smell. The C-O bond in ethers are polar. They are nonlinear (angular) molecules with C-O-C bond angle of about 110⁰. Therefore, ethers are polar compounds and have a net dipole moment. For example, dipole moment of dimethyl ether is 1.3D.

Ethers are isomeric with alcohols. But they do not show hydrogen bonding and association because of their low polarity. The weak polarity of ethers do not appreciably affect their boiling points which are comparable to those of alkanes of comparable molecular mass but are much lower than the boiling points of isomeric alcohols.

Ethers containing upto 3 carbon atoms are soluble in water due to their hydrogen bond formation with water molecules.
The increase in the size of the alkyl group decreases the polar nature of C-O bond and hence it decreases the hydrogen bonding with water. As a result solubility of ethers decreases with increase in the number of carbon atoms. Ethers are soluble in hydrocarbons and other non-polar solvents like benzene.

Extraction of aluminium from bauxite ore

The extraction of aluminium involves two steps that is, purification of bauxite by Baeyer's process and electrolysis of alumina.

1. Purification of bauxite by Baeyer's process
In the Baeyer's process, the bauxite ore is heated with concentrated NaOH solution under pressure (Aluminum is purified by leaching method). The alumina dissolves as sodium meta aluminate. The other materials present in the ore are left as insoluble part. This solution is filtered in ore are left as insoluble part. This solution is filtered off. From the solution Al(OH)3 is precipitated by adding freshly prepared Al(OH)3 to the cold dilute solution and agitating.
Al2O3 + 2NaOH -------> 2NaAlO2 + H2O
NaAlO2 + 2h2o -------> NaOH + Al(OH)3
The precipitated Al(OH)3 is dried and ignited to get pure alumina.
2Al(OH)3 --------> Al2O3 + 3H2O

2. Electrolysis of alumina
The alumina is dissolved in a mixture of molten cryolite and fluorspar which lowers the melting point. It is then electrolysed in a rectangular steel tank with carbon lining, which serves as cathode. Anode is set of thick carbon rods suspended from the top into the fused Al2O3. The temperature is maintained between 1200 and 1310k. Oxygen is evolved at the anode.
Al2O3 -------> 2Al3+ + 3O2-
At cathode: 2Al3+ + 6 electron -------> 2Al
At cathode: 3O2- --------> 1.5 O2 + 6 electron

Aluminium formed at the cathode gets collected at the bottom of the electrolytic cell from where it is removed periodically.
The metal obtained by this method is about 99% pure. Further purification is carried out by Hoop's electrolytic method. The electrolytic refining of aluminum is carried out in Hoop's cell. The cell consist of iron tank having a lining of carbon. It has three layers of molten liquids with different densities. Molten impure aluminum in the bottom layer which along with the carbon lining acts as the cathode. The middle layer is a mixture of molten fluorides of sodium, barium and aluminum in the molten fluorides of sodium, barium and aluminum in the molten state. This act as the electrolyte. Top layer consist of molten pure aluminum in which a number of carbon electrodes are suspended. These carbon electrodes act as the cathode.
When electric current is passed, the aluminium ions from the middle layer move to the top layer and are discharged at the cathode as pure aluminium. At the same time, an equivalent amount of aluminum from the bottom layer migrates to the middle layer leaving behind the impurities. The pure aluminum is removed from the tapping hole from time to time.

For more visit Extraction of aluminium (new)



Related article
Extraction of sulphur
Extraction of copper
Extraction of Sodium

Trends in chemical reactivity of Group 15 elements

Chemical properties of Group 15 elements

1. Phosphorous exhibit covalent character though it can accept three electrons to form phosphides. The covalent character decreases as we move down the group. that is
Phosphorus (P) > Arsenic (As) > Antimony (Sb) > Bismuth (Bi)

2. Group 15 element Forming Hydrides

The element of group 15 form hydrides of the type MH₃. They are NH₃ (Ammonia), PH₃ (Phosphine), AsH₃ (Arsine), SbH₃ (Stibine) and BiH₃ (Bismuthine). Hydrides are covalent and central atom is sp³ hybridized. Due to the presence of lone pair on central atom, they act as lewis bases and has pyramidal shape. The basic strength of hydrides decreases down the group. Thermal stability of hydrides also decreases on moving down the group. Except NH₃ all the hydrides are strong reducing agents and react with metal ions. The reducing character increases in going from NH₃ to BiH₃.

3. Group 15 element Forming Halides

The group 15 elements form two series of halides of the type MX₃ and MX₅.Nitrogen does not form pentahalides because of the absence of d-orbitals in nitrogen. Trihalides are pyramidal in shape and the central atom is in sp³ hybridised state. In pentahalides of group 15 elements, the central atom is in sp³ d hybridization and has trigonal bipyramidal geometry. Phosphorus trichloride ( PCl₃) fumes in moist air because of its reaction with water producing HCl.

PCl₃ + 3H₂O ------------> H₃PO₃ + 3HCl

Phosphorus pentachloride (PCl₅) fumes in air beacuse it react with water to give initially POCl₃ and finally H₃PO₄

PCl₅ + H₂O -----------> POCl₃ + 2HCl

POCl₃ + 3H₂O -----------> H₃PO₄ + 3HCl


4. Group 15 element Forming Oxides

Nitrogen forms five oxides with oxidation state ranging from +1 to +5. They are N₂O (Nitrous oxide), NO (Nitric Oxide), N₂O₃ (Dinitrogen trioxide), N₂O₄ (Dinitrogen tetroxide) and N₂O₅ (Dinitrogen pentoxide). Other elements of group 15 form two types of oxides of the type M₂O₃ and M₂O₅ (M=P,Sb or Bi. Due to reluctance of P,As,Sb and Bi to form pie-pie multiple bonding, their oxides have cage like structure and exist as dimmers (M₄O₆ and M₄O₁₀).

For more chemistry article visit Trends in chemical reactivity of Group 14 elements

Leaching: metallurgy

Leaching is a chemical method for the concentration of the ore. Here the powdered ore is treated with a suitable reagent in which the ore alone dissolves. The impurities are filtered off and from the solution the ore is regenerated by precipitation.

Thus bauxite (Al₂O₃.2H₂O), the ore of aluminum, contain silicon dioxide and oxides of iron and titanium as impurities. The powdered ore is digested with 45% sodium hydroxide solution at 500K and 35 atmosphere pressure. Al₂O₃ forms soluble sodium aluminate (SiO₂ form soluble sodium silicate). The solution is filtered to remove insoluble impurities, diluted with water and seeded with some freshly precipitated Al(OH)₃ which induce the precipitation of Al(OH)₃ from the solution. The precipitate is filtered and heated to get pure alumina (Sodium silicate remain in solution).


Al₂O₃.2H₂O + 2NaOH ----------> 2NaAlO₂ + 3H₂O


NaAlO₂ + 2H₂O -----------> Al(OH)₃ + NaOH


2Al(OH)₃ ------^-----> Al₂O₃ + 3H₂O


For extraction of Aluminum visit Extraction of aluminium from bauxite

Trends in chemical reactivity of Group 14 elements

Chemical properties of Group 14 elements

1. The elements of group 14 form covalent hydrides of the type MH₄. The number of hydrides, their thermal stability and their ease of formation decreases as we move down the group. The reducing power of hydrides increases as we move from CH₄ to PbH₄. Carbon forms a large number of cyclic and acyclic hydrides known as hydro carbons. Si andGe form hydrides of the formula M_nH_2n+2 (where M=si, n=1 to 8; M=Ge, n=1 to 5). The hybrides of silicon are called silanes while those of Germanium are called Germanes. Tin and Lead from one hydride each, ie SnH₄ (Stannane) and PbH₄ (Plumbane).

2. Elements of Group 14 form two types of halides, tetrahalides (MX₄) and dihalides (MX₂)
The tetrahalides are covalent and have tetrahedral geometry. Their thermal stability decreases down the group. The tetrahalides of group 14 except that of carbon are readily hydrolysed.

SiCl₄ + 4H₂O -----------> Si(OH)₄ + 4 HCl

In carbon there is no vacant d -orbitals. Hence it can not increase its valency beyond four. Therefore tetrahalides of carbon are not hydrolysable.
The stability of dihalides of group 14 increases as we descend the group.

3. The elements of group 14 form two types of oxides, monoxides of the type MO and dioxides of the type MO₂. All elements of group 14 except Si form monoxides. Among dioxides, CO₂ exist as linear monomeric molecules because carbon froms Pie - Pie multiple bonds with oxygen (O=C=O). In all other dioxides, group 14 element and oxygen atoms are connected by single covalent bonds forming infinite three dimensional network structures. Hence they exist as solids.