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Leaving Certificate Chemistry
Organic Chemistry 10 – The Alkanes Leaving Certificate Chemistry
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Contents Chemical Structures of the Alkanes Saturated compounds Butane
Isomers Butane Propane Physical Properties & Cyclohexane Chemical Structure Chemical Structure of Cyclohexane Reactions of the Alkanes Formation of a chloroalkane
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Hydrocarbons 1. The Alkanes 2. The Alkenes 3. The Alkynes (Ethyne)
4. Aromatic
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Objectives Today you should learn about.. What a homologous series is
What saturated means and how to test for it What an isomer is and how to name isomers of alkanes
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Homework From the worksheet: Questions 114 - 121
Learn the definitions of : Homologous series, saturated and isomer
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2006 Q. 9 (a) (5)
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The Alkanes: CnH2n+2 These are the main constituents of crude oil
The simplest member is methane Methane – CH4
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The First 8 Alkanes Methane: CH4 Ethane: C2H6 Propane: C3H8
Butane: C4H10
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The First 8 Alkanes Pentane: C5H12 Hexane: C6H14 Heptane: C7H16
Octane: C8H18
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The First 8 Alkanes Structural Formulae
Methane: CH4 Carbon-Carbon Single Bonds Only 1 Carbon-Long H H C H H
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The First 8 Alkanes Structural Formulae
Ethane: C2H6 Used to produce the more useful ethene by catalytic cracking Carbon-Carbon Single Bonds Only 2 Carbon Longest Chain H H H C C H H H
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The First 8 Alkanes Structural Formulae
Propane: C3H8 Carbon-Carbon Single Bonds Only 3 Carbon Longest Chain A constituent of liquid petroleum gas H H H H C C C H H H H H
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The First 8 Alkanes Structural Formulae
Butane: C4H10 Carbon-Carbon Single Bonds Only 4 Carbon Longest Chain H H H H H C C C C H A constituent of liquid petroleum gas H H H H
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The First 8 Alkanes Structural Formulae
Pentane: C5H12 Carbon-Carbon Single Bonds Only 5 Carbon Longest Chain H H H H H H C C C C C H H H H H H
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The First 8 Alkanes Structural Formulae
Hexane: C6H14 Carbon-Carbon Single Bonds Only 6 Carbon Longest Chain H H H H H H H C C C C C C H H H H H H H
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The First 8 Alkanes Structural Formulae
Heptane: C7H16 Carbon-Carbon Single Bonds Only 7 Carbon Longest Chain H H H H H H H H C C C C C C H C H H H H H H H H
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The First 8 Alkanes Structural Formulae
Octane: C8H18 Carbon-Carbon Single Bonds Only 8 Carbon Longest chain H H H H H H H H H C C C C C C C C H H H H H H H H H
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The Alkanes All of these molecules are saturated molecules – They will not decolourise bromine water or acidified potassium permanganate solution
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Isomers
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2 Isomers of butane H H CH3 H H H H C C C C H H H H H 2 - methyl
Methyl Group 2002 Q. 8 (a) (6) H H CH3 H H 1 2 3 H H C C C C H H H H H 2 - methyl Butane propane
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Isomers of butane Butane 2-Methylpropane
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3 Isomers of pentane 2 - methyl Pentane butane 2, 2 - dimethylpropane
2005 Q. 6 (b) (18) 2007 Q. 6 (a) (9) Methyl Group H H CH3 H H H 1 2 3 4 H H C C C C C H H H H CH3 H H H Methyl Group 2 - methyl Pentane butane 2, 2 - dimethylpropane
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Isomers of pentane Pentane 2, 2 - dimethylpropane 2-methylbutane
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Cyclohexane H H H C H H C C H H C C H H C H H H Cyclohexane: C6H12
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Check your learning.. Do you know ? What a homologous series is
What saturated means and how to test for it What an isomer is and how to name isomers of alkanes
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Physical properties of the alkanes
Intramolecular Bonds present - Ionic, polar covalent or covalent? Is the molecule polar overall? ( think of shape) Soluble in a polar or a non polar solvent (like dissolves like) Intermolecular bonds present? Would it have a high boiling point or a low boiling point? Solid gas or liquid at room temperature?
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Physical Properties of the Alkanes
They are all excellent fuels No taste or smell They all burn in air to produce carbon dioxide and water -For Example Pentane C5H O CO H2O
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chemical reactions of the alkanes
Reaction with Chlorine Formation of the Chloroalkanes 2003 Q. 6 (b) (3) 2005 Q. 7(b) (3) A substitution reaction involving ultraviolet light
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The reaction of methane with chlorine
In the presence of ultraviolet light Cl Cl H C H Hydrogen chloride Chlorine H Chloromethane Methane
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The reaction of ethane with chlorine
2003 Q. 6 (d) (9) H H In the presence of ultraviolet light Cl Cl H C C H Hydrogen chloride Chlorine H H Chloroethane Ethane
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The reaction of propane with chlorine
Cl Cl H H H Hydrogen chloride Chlorine H C C C H H H H Propane Chloropropane In the presence of ultraviolet light
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The reaction of butane with chlorine
Cl Cl H H H H Hydrogen chloride Chlorine H C C C C H H H H H Chlorobutane Butane In the presence of ultraviolet light
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The First 4 Chloroalkanes Structural Formulae
Chloromethane: CH3Cl Single Bonds Only Chlorine 1 Carbon-Long H A toxic gas no longer found in consumer products H C Cl H Functional group of atoms
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The First 4 Chloroalkanes Structural Formulae
Chloroethane: C2H5Cl Single Bonds Only Chlorine 2 Carbons-Long H H Aerosol spray propellant H C C Cl H H 2005 Q. 7 (a) (5)
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The First 4 Chloroalkanes Structural Formulae
Chloropropane: C3H7Cl Single Bonds Only Chlorine 3 Carbons-Long H H H H C C C Cl H H H
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The First 4 Chloroalkanes Structural Formulae
Chlorobutane: C4H9Cl Single Bonds Only Chlorine 4 Carbons-Long H H H H H C C C C Cl H H H H
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