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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 a...

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 C 17 H 35 COONa (sodium stearate). In aqueous solution soap ionizes as The RCOO - ions (C 17 H 35 COO - ) and Na + ions. C 17 H 35 COONa ---------> C 17 H 35 COO - + Na + The RCOO - ions however consist of two parts. That is, long hydrocarbon chain R(-C 17 H 35 ) also called non-polar tail which is hydrophobic and the polar group COO - called polar-ionic head which is hydrophilic. In concentrated solution,...

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...

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. H 2 O + CO 2 ------> H 2 CO 3 H 2 CO 3 ------> 2H+ + CO 3 2- The iron is oxidized by the removal of electrons and acts as the anode. Fe ------> Fe 2+ + 2electron The H+ ions from the electrolyte accept electrons from the adjacent areas on metal surface and function as cathode. 4H + + 4electron ------> 2H 2 The atmospheric oxygen moves hydrogen as water. 2H 2 + O 2 ------> 2H 2 O Adding the above two equations, 4H+ +O 2 + 4electron ------> ...

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 ...

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 H 2 SO 4 to remove basic impurities and phenol is then extracted with dilute caustic soda . The aqueous layer is separated and phenol is precipitated with H 2 SO 4 or CO 2 . 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 3...

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, C 2 H 5 -O-C 2 H 5 + HI ------------> C 2 H 5 - I + C 2 H 5 OH On boiling with excess of concentrated Hydrogen iodide (HI), Alkyl iodide is formed. C 2 H 5 -O-C 2 H 5 + 2HI ------------> 2C 2 H 5 I + H 2 O 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 pus...

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 ethano...

Industrial Preparation of Methanol Methanol , CH 3 OH, 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-Cr 2 O 3 catalyst. Co + 2H 2 ----(Cu-ZnO-Cr 2 O 3 , 200-300 atm, 573-673 K)------> CH 3 OH 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

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, C 2 H 5 O 2 H 5 + O ------------> (C 2 H 5 ) 2 O (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

Chemical Properties of Ethers (with H 2 SO 4 ) On heating with dilute sulfuric acid under pressure, ethers are hydrolysed to alcohols. For example, C 2 H 5 OC 2 H 5 + H 2 O ----( dil.H2so4,high pressure )-----> 2C 2 H 5 OH Mixed ethers under similar conditions give a mixture of alcohols. CH 3 OC 2 H 5 + H 2 O ------( dil.H2so4,high pressure )------>C 2 H 5 OH + CH 3 OH But if concentrated sulfuric acid is used, then the products are alcohol and alkyl hydrogen sulphate. C 2 H 5 OC 2 H 5 (Diethyl ether) -----( heat, conc. H2SO4 )-----> C 2 H 5 OH (ethanol)+ C 2 H 5 OSO 2 OH (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

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, PCl 5 , 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 + H 2 O 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 ...

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 H 2 M (where M=O,S,Se,Te or Po). The stability of hydrides decreases as we go down the group. Except H 2 O, 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 sp 3 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 (...

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 110 0 . 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. Et...

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 elect...

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 MH 3 . They are NH 3 (Ammonia), PH 3 (Phosphine), AsH 3 (Arsine), SbH 3 (Stibine) and BiH 3 (Bismuthine). Hydrides are covalent and central atom is sp 3 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 NH 3 all the hydrides are strong reducing agents and react with metal ions. The reducing character increases in going from NH 3 to BiH 3 . 3. Group 15 element Forming Halides The group 15 elements form two series of halides of...

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 (Al 2 O 3 .2H 2 O), 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. Al 2 O 3 forms soluble sodium aluminate (SiO 2 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). Al 2 O 3 .2H 2 O + 2NaOH ----------> 2NaAlO 2 + 3H 2 O NaAlO 2 + 2H 2 O -----------> Al(OH) 3 + NaOH 2Al(OH) 3 ------^-----> Al 2 O ...

Chemical properties of Group 14 elements 1. The elements of group 14 form covalent hydrides of the type MH 4 . 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 CH 4 to PbH 4 . Carbon forms a large number of cyclic and acyclic hydrides known as hydro carbons. Si andGe form hydrides of the formula M n H 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 SnH 4 (Stannane) and PbH 4 (Plumbane). 2. Elements of Group 14 form two types of halides, tetrahalides (MX 4 ) and dihalides (MX 2 ) 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. SiCl 4 + 4H 2 O -----------> Si(OH) 4 + 4 HCl In carbon there is no vacant...