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The important trends observed in the chemical behavior of group 13 elements are 1. Group 13 elements form hydrides of the type MH 3 . Thermal stability of hydrides decreases as we move down the group. Hydrides act as weak lewis acids. Boron forms a number of hydrides known as boranes. The important series among boranes are nido-boranes (B n H n+4 ) and arachno-boranes (B n H n+6 ). Aluminium and Galium can form tetra hydrido anions (MH 4 -).[LiAlH 4 ] is an example for this and is a good reducing agent used in organic synthesis. 2. The elements of group 13 form trihalides of the type MX 3 . The trihalides are strong Lewis acids. The flurides are ionic and have high melting points. The chlorides, bromides and iodides are covalent compounds with low melting points. Halides can exist in dimeric form with halogen bridges. 3. All the elements of group 13 form oxides with formula M 2 O 3 and hydroxides of the type M(OH) 3 . Basic character of oxides and hydroxides increases as we move down...

Trends of chemical properties in group 17 elements 1. Oxidizing property of halogens Group 17 elements are highly electronegative and hence they have strong tendency to accept electrons. Thus halogens act as strong oxidizing agents. F 2 is the strongest oxidizing halogen. A halogen can oxidizes halide ions of higher atomic number. F 2 + 2X - ----------> 2F - + X 2 [X = chlorine (Cl), Bromine (Br) or Iodine (I)] The oxidising ability of halogens decreases as we go down the Group. 2. Formation of Halides Halogens combine with metals, nonmetals and even noble gases to form halides. Metal halides are ionic and their ionic character decreases as M-F > M-Cl > M-Br > M-I Halogens combine with nonmetals and form covalent halides whose bond strength decreases as M-F > M-Cl > M-Br > M-I 3. Hydrides (Hydrogen halides) Halogens combine with hydrogen to form covalent halides of the type HX and are regarded as hydrides. Their acidic and reducing character increas...

Preparation of ethers using sodium alkoxide This is an important laboratory method for the preparation of symmetrical and unsymmetrical ethers. In this method, ethers are prepared by heating an alkyl halide with sodium alkoxide. Ethers containing substituted alkyl groups (secondary or tertiary) may also be prepared by this method. The reaction involves a nucleophilic substitution of halide ion by an alkoxide ion. Thus, good results are obtained if the alkyl halide is primary. If a tertiary alkyl halide is used, an alkene is the only reaction product and no ether is formed. For example, the reaction of CH3CONa with (CH3)3 C-Br gives exclusively 2 -methyl propene. It is because alkoxides are not only nucleophiles but also strong bases. They react with alkyl halides leading to elimination reactions. Since halogen attached to the benzene ring is not reactive, in order to prepare an alkyl aryl ether, a mixture of alkyl halide and sodium phenoxide must be heated. For example, ethyl phenyl et...

Preparation of Ethers by Dehydration of Alcohols When excess of a primary alcohol is heated with protonic acids like conc.H 2 SO 4 or H 3 PO 4 at 413 K , it undergoes dehydration to form an ether . 2R - OH (Alcohol) -----(conc.H 2 SO 4 , 413K)-----> R-O-R (Ether) + H 2 O 2C 2 H 5 OH (Ethanol)-----(conc.H 2 SO 4 , 413K)-----> C 2 H 5 -O-C 2 H 5 (Diethyl ether) + H 2 O But this reaction cannot be used for the preparation of unsymmetrical ethers . The formation of reaction product depends on the reaction conditions. At high temperature, if excess of acid is used dehydration occurs in a different way to form an alkene. For example, ethanol when heated with conc.H 2 SO 4 at 440K undergoes dehydration to give ethylene. CH 3 CH 2 OH -----(conc.H 2 SO 4 , 413K)-----> CH 2 = CH 2 + H 2 O The dehydration of secondary and tertiary alcohols to the corresponding ethers is unsuccessful as alkenes are formed easily in these reactions. The dehydration of alcohols can als...

When sodium salt of phenol ( sodium phenoxide ) is heated at about 400 K with carbon dioxide gas under a pressure of about 4-7 atmospheres and the product acidified, ortho hydroxy benzoic acid ( salicylic acid ) is formed as the main product. Saliccylic acid on actylation using acetic anhydride gives aspirin ( acetyl salicylic acid ). For more reaction of phenol visit Fries rearrangement: Reaction of phenol Coupling Reaction of Phenol Reimer-Tiemann reaction of phenol

Phenol reacts with dilute nitric acid at low temperature (298 k) to yield a mixture of ortho nitro phenl (15 %) and para nitrophenol (30-40 %). The ortho and para isomers of nitrophenol can be separated by steam distilation. O-Nitrophenol is steam volatile due to intra molecular hydrogen bonding while p-nitrophenol is less volatile due to intermolecular hydrogen bonding which causes the association of molecules. But, when nitration is carried out using concentrated nitric acid, phenol is converted to 2,4,6-trinitrophenol known as picric acid . In this reaction nitration is accompanied by oxidation of phenol. Preparation of Picric acid Industrially, picric acid is prepared by treating phenol, first with concentrated H 2 SO 4 which converts it to phenol-2,4-disulphuric acid. This yields picric acid on treating it with conc. HNO 3

Esters of phenols yield phenolic ketones on treatment with anhydrous aluminum chloride . This intermolecular rearrangement is called Fries rearrangement . This reaction involves the migration of an acyl group from phenolic oxygen to ortho and para positions of the aromatic ring with respect to the hydroxyl group. For example, phenyl ethanoate yields ortho- and para- hydroxy aceto phenones. Fries rearrangement is considered better than direct acylation as the yield is good. For more reaction of phenol visit Kolbe's Reaction of Phenol Coupling Reaction of Phenol Reimer-Tiemann reaction of phenol

When an ice cold solution of phenol is treated with an ice cold solution of benzene diazonium chloride in mildly alkaline medium p_hydroxy azo benzene (Azo dye) is formed. This reaction is called coupling reaction. For more reaction of phenol visit Kolbe's Reaction of Phenol Fries rearrangement: Reaction of phenol Reimer-Tiemann reaction of phenol

Group 18 consists of the elements, helium, neon, argon, krypton, xenon, and radon, which are collectively known as noble gases. Due to their chemical inactivity they are also called inert gases. Occurrence and isolation Atmospheric air is the major source of noble gases. Radon is not found in atmosphere and is obtained as thee decay product of 226Ra. The total abundance of noble gases in dry air is approximately 1%. Neon, Argon, Krypton and Xenon are obtained by the liquefaction of dry air and separation of its constituents by fractional distillation. Helium is isolated from natural gas. When natural gas is compressed and liquefied, Helium remains along with unliquefied gas, which contains 2% nitrogen as impurity. N2 is removed by adsorption on charcoal at – 1900C. Atomic and physical properties Electronic configuration Except Helium, all other noble gases have ns2np6 configuration. The electronic configuration of He is IS2. Due to this stable electronic configuration, they have less t...

The oxyacids of chlorine are HCLO (Hypochlorous acid), HCLO2 (Chlorous acid), HCLO3 (Chloric acid) and HCLO4 (Perchloric acid). 1. Hypochloric acid or chloric(1)acid (HCLO) It is formed by passing chlorine gas through water. Cl2(g) + H2O (l) ----------> Na2SO4(aq) + 2 HCl (aq) 2. Chlorous acid or chloric (3)acid (HClO2) It is prepared by treating barium chlorate with sulphuric acid. Ba(ClO2)2 + H2SO4 -----------> 2HClO2 + BaSO4 3. Chloric acid or chloric(5)acid (HClO4) Perchloric acid is prepared by treating barium perchlorate with sulphuric acid. Ba(ClO4)2 + H2SO4 ------------> 2HClO3 + BaSO4 4. Perchloric acid or chloric (6) acid Perchloric acid is prepared by treating barium perchlorate with sulphuric acid. Ba(ClO4)2 + H2SO4 -----------> 2HClO4 + BaSO4 For List of oxyacids visit (picture) oxyacids of chlorine For Other examples of oxyacid visit oxyacids of phosphorous

A perfectly ordered crystal can exist only at absolute zero. Above this temperature some departure from ordered arrangement occurs. These are called imperfection or defects.Crystals contain a group of micro crystals with irregularities at crystals boundaries or grain boundaries. These are called lattice defects. The irregularities may also be present at several lattice points. They are called points defects. Point defects These are defects localized at lattice points or at voids. Thus 1 cm3 of a crystal of NaCl with 10^22 Na+ and 10^22Cl- ions has 10^6 vacant Na+ lattice positions at room temperature. Metallic crystals also contain such vacant lattice positions due to missing of metal atom in the lattice. The lattice positions from which lattice atoms or ions are missing are called vacancies. Thus ionic crystals have cation and anion vacancies. Point defects can also arise due to various other factors and it is convenient to classify them as follows. 1. Stoichiometric defects 2. N...

When phenol is heated with chloroform in presence of aqueous alkali ( NaOH ) at 340 K followed by hydrolysis of the resulting product a -CHO group is introduced at ortho position of benzene ring to form a phenolic aldehyde known as salicylaldehyde (O- hydroxy benzaldehyde) as the main product. A small amount of the para isomer is also obtained. This reaction is known as Reimer - Tiemann reaction. Instead of chloroform, if carbon tetrachloride is used in the above reaction salicylic acid (O- hydroxy benzoic acid) is obtained as the major product.

Reaction of Phenol with neutral Ferric Chloride Phenol reacts with neutral ferric chloride to give a violet coloured water soluble complex. C 6 H 5 OH + FeCl 3 --------------> [Fe(OC 6 H 5 ) 6 ] 3- + 3H + + 3HCl The complex formed is a coordination compound in which iron is hexacovalent. In fact, all compounds, whether aliphatic or aromatic containing the enol group (C=C-OH) but unlike alcohol give characteristics colours with neutral FeCl 3 . Different phenols give different colour. This reaction forms the basis of group test for the enolic grouping and may also be used to disitnguish between different phenols on the basis of the colour obtained.

Alcohols and phenols consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are due to the OH group.The alkyl and aryl groups modify these properties. The boiling points of alcohols and phenols increase with increase in the number of carbon atoms. This is due to increase in van der Waals forces. In alcohols, the boiling points decrease with increase in branching. The reason is that when branching increases, vander Waals forces decreases due to decrease in surface area. The –OH group in alcohols and phenols contain a hydrogen bonded to an electronegative oxygen atom. Therefore, it is capable of forming hydrogen bond. Alcohols and phenols have higher boiling points than the corresponding other classes of compounds namely hydrocarbons, ether and halo alkanes/haloarenes of comparable molecular masses due to the presence of intermolecular hydrogen bonding in them. The solubility of alcohols and phenols in water is due to their ability to ...

 Iron is extracted from its oxide ores. The ores are crushed and concentrated by gravity method. Magnetite is further concentrated by magnetic method. The concentrated ore is calcined to remove volatile impurities and make the ore porous. The calcined ore contains SiO 2 as the chief impurity. It is mixed with lime stone (CaCO 3 ) as flux and coke as reducing agent and the mixture is charged into a blast furnace (a very tall steel tower lined inside with fire bricks). The charge is heated by a hot blast of air preheated at 1000 K blown in through narrow pipes (tuyers) at the base of the furnace. Here coke burns producing heat and temperature rise to 2100 K. C + O 2 --------------> CO 2 + heat The temperature falls to 500 K towards the top of the furnace due to the endothermic reaction. CO 2 + C ---------------> 2CO - heat Carbon monoxide reduces iron oxide to iron in the middle and upper regions of the furnace. 3Fe 2 O 3 + CO -----------------> 2Fe 3 O 4...

 As sodium is a highly electro positive metal it cannot be prepared by the usual methods of reduction. The metal is extracted by the electrolysis of a molten mixture of NaCl, CaCl 2 and KF in a Downs cell at 600 degree Celsius. The cell has a graphite anode and a circular iron cathode, both covered and with proper outlets. Chlorine liberated at the cathode rises up through a pipe and gets collected in a receiver in the molten state. NaCl ------> Na + + Cl - Na + + e - -------> Na (At cathode)  2Cl - --------> Cl 2 + 2e - (At anode) The electrolysis of NaCl presents some difficulties. The fusion temperature of pure NaCl is 803 degree celsius. At this temperature both Na and Cl 2 are highly corrosive. Addition of CClCl 2 and KF reduce the fusion temperature to 600 degree celsius. Did you Know how the extraction of aluminum is done ? visit for more details extraction of aluminum