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How do youaccount for thefollowing?(a) Alkanes are accountfor thefollowing ? (B) chorination of methanedoesno chemical reagents . ( C)iodinatio of methaneoccursof methaneocursin presenceof iodicacid . (d) why thecreackedgasolineis consideredto besuperior to staught distilled gasoline ( e) theboilingpointsof branched chainalkanesarelower thanthan theirnormalisomers . ( f) Alkanes containingeven numberof carbon atoms have higher than expected point . (g) Although combustion of alkanes is a strongly exo0thermic proces it doesnot occur at moderate temperature (h) thetraethyl lead Pn (CH_(2) H_(5) )_(4)initiales the chlorinationof methanein thedarlk at 423 K . (j) why doesan oil slick form on thesurface of the ocean aftera spill ? ( j) Atetriary carbon atomcan be oxidisedwithrelativeease . (K) Out of 2-methyhexaneand 2,2- dimethylbutanewhichone hashigherpointand whichone has higherboiling point? |
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Answer» Solution :(A) Alkanes haveno reactionsites due to C-C and C-H non polar BONDS where thechemicalregentscan attack . ( B)Chlorinationis a freeradicalsubstition , to get chorine freeradicals fromCl_(2) moleculesenergyis requiredwhichis notavailableindark. ( C) Iodinationis areversiable processtodecomposehydrogeniodine , oneof theproducts,anoxidisingagent i.e, iodicacidisrequired , `(5HI+HIO_(3)to 3I_(2) +3H_(2)O)` (D) Creakedgasolineposseses branchedchainhydrocarbons whichhavehigheroctanenumberthe straightdistilleddistilledgasoline possesmainlystright chain hydrocarbons . ( E)theintermolecularforcesareweaker inbranchedchainisomers dueto lowsurfacearea andtherefore, havelowerboilingpoints . ( f)Alkaneswitheven numberof carbon atomspackin amanner todueto lowsurfacearea andtherefore, haveslightlyhigermelting points. (G) thereactionis veryslowat room temperaturebecauseof a veryhighenergyfo activation . (H) `Pb(C_(2)H_(5))_(4)` undergoesthermolhomolysisof C-Pb bondat423K , thefreeradical `CH_(3)CH_(2)`thengenertates `overset(*)Cl`whichbringschlorination of methanein dark. (i) Alanes , thechiefbeing constituent of petroleiumare insolubleand have a lowerdensitythanwater , (j)Alkylgroup beingelectron releasinggoupincreasetheelectron DENSITY at tertiary carbon atom which helpseasy oxidation . (K)the moreis branching HIGHER is the melting POINT and loweristhe boilingpoint, somelting point of 2,2,-dimehtylbutane (morebeanching ) ishigerthanthat of 2- methyhexane(lessbranching ): but the boilingpointof 2-methyhexane is higer thanthatof 2,2 dimethylbutane . |
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