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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...