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Organic Chemistry. Alkanes. Alkanes. Contain C and H only Contain single bonds C-C Have 4 bonds to every carbon (C) atom Are nonpolar. Complete Structural Formulas. Show the bonds between each of the atoms H H H C H H C H
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Organic Chemistry Alkanes
Alkanes • Contain C and H only • Contain single bonds C-C • Have 4 bonds to every carbon (C) atom • Are nonpolar Timberlake LecturePLUS
Complete Structural Formulas Show the bonds between each of the atoms H H H C H H C H H H CH4 , methane Timberlake LecturePLUS
More Alkanes H H Condensed Structural Formulas H C C H CH3 CH3 H H Ethane H H H H C C C H CH3 CH2 CH3 H H H Propane Timberlake LecturePLUS
IUPAC Names Name # carbons Structural Formula Methane 1 CH4 Ethane 2 CH3CH3 Propane 3 CH3CH2CH3 Butane 4 CH3CH2CH2CH3 Pentane 5 CH3CH2CH2CH2CH3 Timberlake LecturePLUS
IUPAC NAMES Name # carbons Structural Formula Hexane 6 CH3CH2CH2CH2CH2CH3 Heptane 7 CH3CH2CH2CH2CH2CH2CH3 Octane 8 CH3CH2CH2CH2CH2CH2CH2CH3 Nonane 9 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3 Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 Timberlake LecturePLUS
Alkanes Alkanes are a family of hydrocarbons containing only single bonds between the carbon atoms
CH4 Molecular formula Methane Tetrahedral Expanded structural formula: showing each bond line.
C2H6 Molecular formula Condensed structural formula:with each carbon atom and its attached hydrogen atoms. CH3 – CH3 Ethane Expanded structural formula
Alkanes HomologousSeriesgeneral formulaCnH2n+2 n: number of carbonatoms
Naming of Alkanes CnH2n+2 Prefix + ane
Carbon-to-carbon chains can be (A) straight, (B) branched, or (C) in a closed ring. • (Some carbon bonds are drawn longer, but are actually the same length.)
Review • Work through the Sample Problem page 175 • Complete the revision questions page 175 (1 – 3)
Learning Check Alk1 A. What is the condensed formula for H H H H H C C C C H H H H H B. What is its molecular formula? C. What is its name? Timberlake LecturePLUS
Solution Alk1 A. CH3CH2CH2CH3 B. C4H10 C. butane Timberlake LecturePLUS
Reactions of Alkanes • Alkanes burn in oxygen to form carbon dioxide and water - oxidation or combustion reaction • CH4(g) + O2(g) CO2(g) + 2H2O(g) • Alkanes react with chlorine or fluorine in a reaction called a substitution reaction (one of the chlorine or fluorine atoms takes the place of one or more of the hydrogen atoms
Reactions of Alkanes Combustion alkane + O2 CO2 + H2O + heat Timberlake LecturePLUS
Combustion In the Cell Metabolic oxidation is combustion C6H12 O6 + 6O2 6CO2 + 6H2O + heat glucose Timberlake LecturePLUS
Learning Check Alk2 Complete the combustion reaction for C3H8 + O2 + Balance your equation Timberlake LecturePLUS
Solution Alk2 Step 1 C3H8 + O2 CO2 + H2O Step 2 C3H8 + O2 3 CO2 + 4 H2O Step 3 C3H8 + 5 O2 3 CO2 + 4 H2O Timberlake LecturePLUS
Learning Check Alk3 Complete and balance the reaction for the complete combustion of C7H16 Timberlake LecturePLUS
Solution Alk3 Step 1 C7H16 + O2 CO2 + H2O Step 2 C7H16 + O2 7 CO2 + 8 H2O Step 3 C7H16 + 11 O2 7 CO2 + 8 H2O Timberlake LecturePLUS
Review • Complete the revision questions page 175 (4 - 6)
Isomers • Straight chain alkanes: An alkane that has all its carbons connected in a row. • Branched chain alkanes: An alkane that has a branching connection of carbons. • Isomers: Compounds with same molecular formula but different structures.
There is only one possible way that the carbons in methane (CH4), ethane (C2H6), and propane (C3H8) can be arranged.
However, carbons in butane (C4H10) can be arranged in two ways; four carbons in a row (linear alkane) or a branching (branched alkane). These two structures are two isomers for butane.
Different isomers are completely different compounds. They have different structures, different physical properties such as melting point and boiling point, and may have different physiological properties.
Review • Complete revision questions page 176 (7 – 9) Timberlake LecturePLUS