12343.docx - Assignment Topic : Economic important of...

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AssignmentTopic:Economicimportantofalkanes,alkenes,alkynesStudent Name:.Student ID :.
AlkanesAlkanes are used to prepare black carbon, water gas, alkyl halides, alcohols, and aldehydes,They are homologous series as each compound exceeds the previous one by (– CH2) group,They have a general molecular formula, the same chemical properties and graduated inphysical properties, Liquid and gaseous alkanes are used as fuel. The figure 1 shows the bondof alkanes(Figure 1)Physical properties of alkanesThe first four members of alkanes are gases at normal temperature, Methane can be used asfuel at homes, while the mixture of propane & butane is liquified and packed in cylinders , Itis used as fuel (butagas), since propane more volatile ( less boiling point) than butane, so wefind that the ratio of propane is much more in cold countries, while in warm countries thecylinders contain larger ratio of butane. Alkanes which contain from (5 : 17) carbon atomsare liquids such as gasoline and kerosine which are used as liquid fuel, The compounds whichcontain more than 17 carbon atoms are solids such as paraffin wax, with increasing numberof carbon atoms (molecular mass) in alkane, The boiling point of alkanes will increasesbecause as the molecular mass increases, the boiling point increases.Alkanes are non-polarcompounds and insoluble in water, but they are soluble in organic solvents, So the metals arecovered by a heavy layer of alkanes like grease to protect them against rust and corrosion,The boiling point and melting point increase by increasing number of C atoms.Chemical properties of alkanesAlkanes are comparatively, inactive compounds because the carbon atoms in alkanes arecombined together by the strong sigma bonds, these bonds can’t be broken easily exceptunder certain conditions such as burning, substitution and thermal catalytic cracking.Alkanesare chemically unreactive, they are neither affected by mineral acids at room temperature noraffected by oxidizing agents such as KMnO4 or K2Cr2O7, This is due to the presence ofsigma bond (σ) which is difficult to be broken.
Economic importance of AlkanesAlkanes are used to obtain finely divided carbon (black carbon) by thermal cracking, Theblack carbon is produced by heating methane to 1000° C in the absence of air, Black carbonis used in the manufacture of car tires, black painting, polishes, and printing ink.CH4 (g) → C(s) + 2 H2 (g)Alkanes are used to obtain water gas, water gas is a mixture of hydrogen and carbonmonoxide which is used as a reducing agent or as a flammable fuel, Hydrogen gas formed bythis reaction is used in several industries such as in the manufacture of ammonia gas, Watergas is used in medrix furance to reduce Fe2O3 to FeH2O (l) + CH4 (g) → 3H2 (g) + CO (g)Methane is used as fuel in houses but a mixture of propane and butane (liquid) is filled incylinders and used as a fuel (Butagas) since propane is more volatile than butane, in coldcountries, the ratio of propane is more, in warm countries, the cylinders contain a larger ratioof butane.

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