Topic 12 0.0 / 5 ? ChemistryAlkanesASAQA Created by: Jemma1494Created on: 06-06-21 12:03 Crude oil A mixture of different hydrocarbons that can be separated via fractional distillation to obtain the useful small chain alkanes 1 of 18 Halogen alkane Formed via free radical substitution A halogen replaces a hydrogen The reaction leaves a halogen alkane and hydrogen halogen e.g CH4+ Br2 -> CH3Br + HBr 2 of 18 Trends of alkanes Melting and boiling points increase as chain length increases due to stronger van der waal forces Insoluble in H2O Relatively unreactive 3 of 18 Complete combustion Produces CO2 and H2O 4 of 18 Incomplete combustion Produces CO and H2O 5 of 18 Free radical substitution steps Initiation Propagation Termination 6 of 18 Initiation Free radicals are formed Cl2 -> 2Cl’ 7 of 18 Propagation Steps that involve the free radicals reacting with alkanes CH4 + Cl’ -> HCl + CH3’ CH3’ + Cl2 -> CH3Cl + Cl’ 8 of 18 Termination Combining the free radicals 2Cl’ -> Cl2 2CH3’ -> C2H6 CH3’ + Cl’ -> CH3Cl 9 of 18 Cracking of alkanes Done with high temp and pressure (700-1200k) (7000kPa) Breaks long chain hydrocarbons to more useful smaller ones 10 of 18 Catalytic cracking Zeolite catalyst used (Honeycomb structure = large surface area) (Acidic) Lower temp and pressure (720k) 11 of 18 Nitrogen oxides Forms acid rain 12 of 18 Sulfur dioxide Forms acid rain 13 of 18 Carbon particles Asthma and causes cancer Global dimming as particles are in the air 14 of 18 Unburnt hydrocarbons Global warming 15 of 18 Carbon dioxide Global warming 16 of 18 Carbon monoxide Poisonous gas 17 of 18 Removing pollutants Internal combustion engines use catalytic converters to break down harmful pollutants 18 of 18
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