General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.1 Chapter 11 Introduction to Organic Chemistry: Alkanes 11.4 Properties of Alkanes

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.2 Some Properties of Alkanes The properties of alkanes include being  nonpolar  insoluble in water  less dense than water  flammable in air

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.3 Alkanes with 1 – 4 Carbon Atoms Alkanes with 1–4 carbon atoms are  methane, ethane, propane, and butane  gases at room temperature  used as heating fuels

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.4 Alkanes with 5 – 17 Carbon Atoms Alkanes with 5–8 carbon atoms are  liquids at room temperature  pentane, hexane, heptane, and octane  very volatile  used to make gasoline Alkanes with 9–17 carbon atoms  are liquids at room temperature  have higher boiling points  are found in kerosene, diesel, and jet fuels

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.5 Alkanes with 18 or More Carbon Atoms Alkanes with 18 or more carbon atoms  have high molar masses  are waxy solids at room temperature  are used in waxy coatings of fruits and vegetables

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.6 Boiling Points of Alkanes Boiling points of alkanes  are lowest of the organic compounds  increase with larger molecules due to increased dispersion forces  decrease for branched alkanes  increase for cycloalkanes

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.7 Boiling Points of Alkanes with 5 Carbons

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.8 Learning Check For the following pairs of hydrocarbon, which one has the higher boiling point? Why? A. Butane or octane B. Hexane or 2,3-dimethylbutane

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.9 Solution For the following pairs of hydrocarbon, which one has the higher boiling point? Why? A. Butane or octane octane (has more carbon atoms) B. Hexane or 2,3-dimethylbutane hexane (both have 6 carbons, but hexane is not branched)

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.10 Crude Oil The hydrocarbons in crude oil are  separated by their different boiling points  heated to higher temperatures to produce gases that can be cooled and removed

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.11 Crude Oil (continued)

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.12 Combustion of Alkanes Alkanes  undergo combustion by reacting with oxygen to produce carbon dioxide, water, and energy  are typically not very reactive due to strong C—C single bonds Alkane + O 2 (g) CO 2 (g) + H 2 O(g) + energy

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.13 Write the equation: C 5 H 12 (l) + O 2 (g) CO 2 (g) + H 2 O(g) Balance C: C 5 H 12 (l) + O 2 (g) 5CO 2 (g) + H 2 O(g) Balance H: C 5 H 12 (l) + O 2 (g) 5CO 2 (g) + 6H 2 O(g) Balance O with O 2 : C 5 H 12 (l) + 8O 2 (g) 5CO 2 (g) + 6H 2 O(g) Balancing A Combustion Equation

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.14 Learning Check Propane is used to provide heat for cooking or warming a room. Write a balanced equation for the complete combustion of propane.

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.15 Solution Unbalanced equation: C 3 H 8 (g) + O 2 (g) CO 2 (g) + H 2 O(g) Balance C: C 3 H 8 (g) + O 2 (g) 3CO 2 (g) + H 2 O(g) Balance H: C 3 H 8 (g) + O 2 (g) 3CO 2 (g) + 4H 2 O(g) Balance O: C 3 H 8 (g) + 5O 2 (g) 3CO 2 (g) + 4H 2 O(g)

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.16 Write a balanced equation for the reaction for the complete combustion of heptane, C 7 H 16. Learning Check

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.17 Write a balanced equation for the reaction for the complete combustion of heptane, C 7 H 16. C 7 H 16 (l) + O 2 (g) CO 2 (g) + H 2 O(g) C 7 H 16 (l) + O 2 (g) 7CO 2 (g) + 8H 2 O(g) C 7 H 16 (l) + 11O 2 (g) 7CO 2 (g) + 8H 2 O(g) Balanced equation: C 7 H 16 (l) + 11O 2 (g) 7CO 2 (g) + 8H 2 O(g) Solution