Alkanes

Timberlake LecturePLUS2 Alkanes Contain C and H only Contain single bonds C-C Have 4 bonds to every carbon (C) atom Are nonpolar

Timberlake LecturePLUS3 Complete Structural Formulas Show the bonds between each of the atoms H H  H  C  HH C H  H H CH 4, methane

Timberlake LecturePLUS4 More Alkanes H HCondensed Structural Formulas H C C HCH 3 CH 3 H HEthane H H H H C C C HCH 3 CH 2 CH 3 H H H Propane

Timberlake LecturePLUS5 IUPAC Names Name# carbons Structural Formula Methane1CH 4 Ethane2CH 3 CH 3 Propane3CH 3 CH 2 CH 3 Butane4CH 3 CH 2 CH 2 CH 3 Pentane5CH 3 CH 2 CH 2 CH 2 CH 3

Timberlake LecturePLUS6 IUPAC NAMES Name # carbons Structural Formula Hexane 6 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 Heptane 7 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Octane 8 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Nonane 9 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Decane 10 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3

Alkanes Alkanes are a family of hydrocarbons containing only single bonds between the carbon atoms

Methane Tetrahedral Expanded structural formula: showing each bond line. CH 4 Molecular formula

Ethane C2H6C2H6 Molecular formula Expanded structural formula CH 3 – CH 3 Condensed structural formula: with each carbon atom and its attached hydrogen atoms.

Alkanes Homologous Series general formulaC n H 2n+2 n: number of carbon atoms

Naming of Alkanes C n H 2n+2 Prefix + ane

No of C atoms Prefix 1meth- 2eth- 3prop- 4but- 5pent- 6hex- 7hept- 8oct- 9non- 10dec-

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)

Timberlake LecturePLUS15 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 LecturePLUS16 Solution Alk1 A.CH 3 CH 2 CH 2 CH 3 B. C 4 H 10 C.butane

17 Reactions of Alkanes Alkanes burn in oxygen to form carbon dioxide and water - oxidation or combustion reaction CH 4 (g) + O 2 (g) CO 2 (g) + 2H 2 O(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

Timberlake LecturePLUS18 Reactions of Alkanes Combustion alkane + O 2 CO 2 + H 2 O + heat

Timberlake LecturePLUS19 Combustion In the Cell Metabolic oxidation is combustion C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + heat glucose

Timberlake LecturePLUS20 Learning Check Alk2 Complete the combustion reaction for C 3 H 8 + O 2 + Balance your equation

Timberlake LecturePLUS21 Solution Alk2 Step 1 C 3 H 8 + O 2 CO 2 + H 2 O Step 2 C 3 H 8 + O 2 3 CO H 2 O Step 3 C 3 H O 2 3 CO H 2 O

Timberlake LecturePLUS22 Learning Check Alk3 Complete and balance the reaction for the complete combustion of C 7 H 16

Timberlake LecturePLUS23 Solution Alk3 Step 1 C 7 H 16 + O 2 CO 2 + H 2 O Step 2 C 7 H 16 + O 2 7 CO H 2 O Step 3 C 7 H O 2 7 CO H 2 O

Review Complete the revision questions page 175 (4 - 6)

Isomers Straight chain alkanes: An alkane that has all its carbons connected in a row. 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. Branched chain alkanes: An alkane that has a branching connection of carbons. Isomers: Compounds with same molecular formula but different structures. Isomers: Compounds with same molecular formula but different structures.

There is only one possible way that the carbons in methane (CH 4 ), ethane (C 2 H 6 ), and propane (C 3 H 8 ) can be arranged. There is only one possible way that the carbons in methane (CH 4 ), ethane (C 2 H 6 ), and propane (C 3 H 8 ) can be arranged.

However, carbons in butane (C 4 H 10 ) 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.

29 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 LecturePLUS31