7 The Alkanes: molecular formula or displayed formula? Methane CH4Ethane C2H6Propane C3H8Butane C4H10Pentane C5H12Hexane C6H14Octane C8H18
8 The alkanes CnH2n + 2 Methane CH4 Ethane C2H6 Propane C3H8 General formulaMethane CH4Ethane C2H6Propane C3H8Butane C4H10Pentane C5H12Hexane C6H14Octane C8H18Homologous series:Same general formula, similar chemical properties but a graduation in physical properties
9 You have to be able to explain this The alkanes CnH2n + 2General formulaCOPY!Methane CH4Ethane C2H6Propane C3H8Butane C4H10Pentane C5H12Hexane C6H14Octane C8H18You have to be able to explain thisGenerally unreactive, but burn exothermically. Longer chains burn less easily.
16 Combustion Hydrocarbons combust well. What does this mean? What do you predict the products are of this reaction?They burn producing carbon dioxide and waterWrite a word equation for this reaction, then try a chemical equationFor example, with methane:CH4 + 2O2 CO2 + 2H2O
17 Incomplete combustion How do you think this reaction is different?What do you think the products are this time?Why is this reaction so dangerous?Who should be careful?Hurricane Ike link
18 Incomplete combustion When there is insufficient oxygen, carbon monoxide is also formedIt reduces the blood’s oxygen carrying capability
20 Chlorination of Methane Alkanes react with chlorine in sunlight:CH4 + Cl2 CH3Cl + HClHow would you describe this reaction?A chlorine atom takes the place of a hydrogen atom = substitution reaction.What would happen if lots more chlorine was present?