1. GS105: Chapter 12
Energy & Hydrocarbons
Hydrocarbons
Aromatics
Fuel

2. Properties of Organic Compounds
An organic compound
Is a compound made from carbon atoms.
Has one or more C atoms.
Has many H atoms.
May also contain O, S, N, and halogens.
Typical organic compounds
Have covalent bonds.
Have low melting points.
Have low boiling points.
Are flammable.
Are soluble in nonpolar solvents.
Are not soluble in water.
Oil (organic) and
water (inorganic)

3. Organic vs. Inorganic
Propane, C3H8, is an organic compound used as a fuel.
NaCl, salt, is an inorganic compound composed of Na+ and Cl− ions.
Why is propane an
organic compound, but
NaCl is not?
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4. Organic vs. Inorganic Ionic Polar most H2O sol Covalent Nonpolar
C3H8 (propane)
Inorganic
NaCl (salt)
Bonding
Polarity,
Solubility
Melting point
Boiling point
Flammability
Covalent
Ionic
Nonpolar
Polar
most H2O sol
not H2O sol
Low
-188oC
High
800oC
Low
-42oC
High
1413oC
High
Low

5. Learning Check Identify each characteristic as most typical of
compounds that are (I) inorganic or (O) organic.
1. Has a high melting point
2. Is not soluble in water
3. Has a formula CH3─CH2─CH3
4. Has a formula MgCl2
5. Burns easily in air
6. Has covalent bonds

6. Solution Identify each characteristic as most typical of
compounds that are (I) inorganic or (O) organic.
I Has a high melting point
O Is not soluble in water
O Has a formula CH3─CH2─CH3
I Has a formula MgCl2
O Burns easily in air
O Has covalent bonds

7. Combustion of Hydrocarbons
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.
Hydrocarbon + O2  CO2 + H2O + energy

8. Learning Check Propane is used to provide heat for
cooking or warming a room. Write a
balanced equation for the complete
combustion of propane.

9. Solution C3H8 + 5O2  3CO2 + 4H2O (Balanced) Unbalanced equation
Balance C
C3H8 + O2  3CO2 + H2O
Balance H
C3H8 + O2  3CO2 + 4H2O
Balance O
To balance the atoms in the formula C3H8, we place a coefficient of 3 in front of CO2 and a coefficient of 4 in front of H2O. The total O in the products is 10 O (6 O in 3CO2 and 4 O in 4 H2O). To balance the 10 O, a coefficient of 5 is placed in front of the O2.
C3H8 + 5O2  3CO2 + 4H2O (Balanced)

10. Learning Check
Write a balanced equation for the reaction for the complete combustion of heptane C7H16.

11. Solution C7H16 + 11O2  7CO2 + 8H2O C7H16 + O2  CO2 + H2O
Balanced equation:
C7H O2  7CO2 + 8H2O

12. Learning Check
Write the combustion reaction for ethane and balance.

13. Solution 2C2H6 + 7O2  4CO2 + 6H2O balanced
Write the combustion reaction for ethane and balance.
ethane CH3CH3 = C2H6
C2H O2  2CO H2O
C2H O2  2CO H2O
C2H /2 O2  2CO H2O
Multiply through by 2 to clear fraction
2C2H O2  4CO H2O balanced

14. Less than 0
Boiling points
(oC)
35-100
35-215
35-300

15. Fractional Distillation of Crude Oil
The hydrocarbons in crude oil are
Separated by boiling points.
Heated to higher temperatures to produce gases that can be removed and cooled.

16. Octane Rating
Catalytic cracking/Reforming

17. BP
Crude Oil Refinery
(Distillation Tower)
Carson, California

19. Writing Formulas for Carbon Compounds
In carbon compounds
Carbon has 4 valence electrons and hydrogen has 1. •
• C • H •
To achieve an octet, C forms four bonds.
H H
 
H  C  H H C H
H H CH4 , methane

20. Structural Formulas
Alkanes are written with structural formulas that are
Expanded to show each bond.
Condensed to show each carbon atom and its attached hydrogen atoms.
Expanded Condensed H
H C H CH4 , methane
In methane, CH4 the four valence electrons of carbon are shared with the single electrons of four hydrogen (H) atoms. Each pair of electrons is a single bond, which can be drawn as a line. When a structure is drawn to show each bond, it is called a complete structural formula.

21. Organic Compounds with More Carbon Atoms
In organic molecules with more carbon atoms,
Valence electrons are shared.
Covalent bonds form between carbon and carbon atoms.
Covalent bonds form between carbon and hydrogen atoms.
H H H H
• • • •
H  C  C  H H C C H
H H H H
ethane, CH3─CH3

22. Tetrahedral Structure of Carbon
In molecules with two or more carbon atoms, each carbon atom with four single bonds has a tetrahedral shape.

23. Expanded and Condensed Structures
Structural formulas

24. Names of Alkanes The names of alkanes
Are determined by the IUPAC (International Union of Pure and Applied Chemistry) system.
Use a prefix to indicate the number of carbons in a chain.
End in –ane.

25. Learning Check A. Give the name of each compound: 1) CH3—CH3
2) CH3—CH2—CH3
3) CH3—CH2—CH2—CH2—CH2—CH3
B. Write the condensed structural formula of
pentane.

26. Solution A. Give the name of each compound: 1) CH3—CH3 ethane
2) CH3—CH2—CH3 propane
3) CH3—CH2—CH2—CH2—CH2—CH3
hexane
B. Write the condensed structural formula of pentane.
CH3—CH2—CH2—CH2—CH3

27. Line-Bond Formulas
Because each C atom has a tetrahedral arrangement, the order of atoms is not a straight line, but a zigzag pattern.
A line-bond formula abbreviates the carbon atoms and shows only the zigzag pattern of bonds from carbon atom to carbon atom.

28. Conformations The groups attached to a C-C single bond
Rotate around the bond,
Give different relative arrangements called conformations.
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29. Conformations of Butane
Rotation of the end CH3- provides different conformations for butane.
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30. Some Structures for Butane

31. Hexane has Six Carbon Atoms
Is an alkane with 6 carbon atoms in a continuous chain.
Has a “zig-zag” look because each carbon atom is at the center of a tetrahedron.
Is represented by a ball-and-stick model as
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32. Learning Check A. Write the condensed formula for: H H H H H
H C C C C C H
H H H H H
B. What is its molecular formula?
C. What is its name?

33. Solution
A. CH3CH2CH2CH2CH3
B. C5H12
C. pentane

34. Learning Check Write the condensed structural formula for A. ethane
B. heptane

35. Solution Write the condensed structural formula for A. ethane CH3─CH3
B. heptane CH3─CH2─CH2─CH2─CH2─CH2─CH3

36. Cycloalkanes Cycloalkanes Are cyclic alkanes.
Have 2H fewer than the open chain.
Are named by using the prefix cyclo- before the name of the alkane chain with the same number of carbon atoms.
Cyclopropane
Cyclobutane
Cyclopentane
Cyclohexane

37. Learning Check Name the following: A. CH3─CH2─CH2─CH3 B.
C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 D.

38. Solution Name the following: A. CH3─CH2─CH2─CH3 butane B. cyclopropane
C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 octane D.
cyclohexane

39. Isomers of Butane Isomers Have the same molecular formula.
Have different atom arrangements.
Of butane (C4H10) consist of a straight chain and a branched chain each with 4 carbon atoms.
branch
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40. Naming Substituents In the IUPAC system,
A carbon branch is named as an alkyl group.
Halogen atoms are named as halo.

41. Naming Substituents In the IUPAC system,
Names of side groups
methyl
ethyl
propyl
Isopropyl
n-butyl
sec-butyl
Isobutyl
tert-butyl or
t-butyl
In the IUPAC system,
A carbon branch is named as an alkyl group.
Halogen atoms are named as halo.

42. Naming Substituents In the IUPAC system,
Names of side groups
Fluoro
Chloro
Bromo
Iodo
Hydroxy
In the IUPAC system,
A carbon branch is named as an alkyl group.
Halogen atoms are named as halo.

43. Alkanes with Alkyl Groups
CH3
CH3 CH CH methylpropane
methyl groups
CH CH3
CH3 CH CH2 CH CH ,4-dimethylpentane

44. Guide to Naming Alkanes
Give the name of CH3 CH3
 
CH3─CH─CH─CH3
STEP Longest chain is butane.
STEP Number chain. CH3 CH3
 
STEP 3 Locate substituents and name.
2,3-dimethylbutane

45. Learning Check
Write the IUPAC name for
Cl CH3
 
CH3─CH2─CH─CH─CH3

46. Solution STEP 1 Longest chain is pentane.
STEP Number chain from end nearest substituent.
Cl CH3 (nearest end)
 
CH3─CH2─CH─CH─CH3
STEP 3 Locate substituents and name alphabetically.
3-chloro-2-methylpentane

47. Learning Check Give the IUPAC name for the following: CH3 CH3 | |
| |
CH3─CH─CH2 ─CH─CH2─CH3

48. Solution A. CH3 CH3 | | CH3─CH─CH2 ─CH─CH2─CH3 2,4-dimethylhexane
| |
CH3─CH─CH2 ─CH─CH2─CH3 2,4-dimethylhexane
2, 4-dimethylhexane
2, dimethyl hexane
Location of Two CH3- groups carbon main chain
branches on attached with single C-C bonds
main chain

49. Learning Check Draw the condensed structural formula for
2-bromo-4-chlorobutane.

50. Solution STEP 1 Longest chain has 4 carbon atoms. C─C─C─C
STEP Number chain and add substituents. Br 
C ─ C ─ C ─ C ─ Cl
STEP 3 Add hydrogen to complete 4 bonds to each C.
CH3─CH─CH2─CH2─Cl

51. Learning Check
Write three isomers of C5H12 and name each.

52. Solution A chain of 5 carbon atoms CH3─CH2─CH2─CH2─CH3
pentane
A chain of 4 carbon atoms and 1 carbon branch
CH3 │
CH3─CH─CH2─CH methylbutane
A chain of 3 carbon atoms and 2 carbon branches
CH3─C─CH3 2,2-dimethylpropane

53. Alkanes with 1-4 Carbon Atoms
Gases
Alkanes with 1-4 carbon atoms are
Methane, ethane, propane, and butane.
Gases at room temperature.
Used as heating fuels.

54. Alkanes with 5-17 Carbon Atoms
Liquids
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.

55. Alkanes with 18 or more Carbon Atoms
Solids
Alkanes with 18 or more carbon atoms
Have high molar masses.
Are waxy solids at room temperature.
Used in waxy coatings of fruits and vegetables.

56. Boiling Points of Pentanes
BPs of alkanes
Are lowest of organic compounds.
Increase with larger molecules due to increased dispersion forces.
Decrease for branched alkanes.
Increase for cycloalkanes.

57. Learning Check For the following pairs of hydrocarbon, which one has
the higher boiling point? Why?
1. butane or octane
2. hexane or 2,3-dimethylbutane

58. Solution For the following pairs of hydrocarbon, which one has
the higher boiling point? Why?
1. butane or octane octane has more carbon atoms
2. hexane or 2,3-dimethylbutane
hexane is not branched

59. Heteroatoms in Organic Compounds
In organic molecules,
C atoms form bonds
Mostly with H and other C atoms.
Sometimes Heteroatoms: atoms of O, N, S, and halogens F, Cl, and Br.

60. Functional Groups Functional groups are
A characteristic feature of organic molecules that behave in a predictable way.
Composed of an atom or group of atoms.
Groups that replace a H in the corresponding alkane.
A way to classify families of organic compounds.

61. Some Functional Groups

62. Unsaturated Hydrocarbons
Alkenes
Alkynes
Unsaturated hydrocarbons
Have fewer hydrogen atoms attached to the carbon chain than alkanes.
Are alkenes with double bonds.
Are alkynes with triple bonds.
ethylene
acetylene
Is used as fuel for welders torches.
Is used to accelerate the ripening of fruits.

63. Naming Alkenes & Alkynes
Use the corresponding alkane name.
Change the ending to ­ene or -yne
Alkene IUPAC Common
H2C=CH2 ethene ethylene
H2C=CH─CH3 propene propylene
cyclohexene
Alkyne IUPAC Common
HC≡CH ethyne acetylene
HC≡C─CH3 propyne

64. Comparing Names of Alkanes, Alkenes, and Alkynes

65. Naming Alkenes Write the IUPAC name for CH2=CH─CH2─CH3 and
STEP 1 Name the longest carbon chain
butene
STEP 2 Number the chain from the double bond
CH2=CH─CH2─CH3 1-butene
CH3─CH=CH─CH3 2-butene

66. Naming Alkenes with Substituents
CH3 │
Write the IUPAC name for CH3─CH─CH=CH─CH3
STEP 1 Name the longest carbon chain pentene
STEP 2 Number the chain from the double bond
CH3─CH─CH=CH─CH pentene
STEP 3 Give the location of each substituent
4-methyl- 2-pentene

67. Naming Alkynes with Substituents
CH3 │
Write the IUPAC name for HC≡C─CH─CH3
STEP 1 Name the longest carbon chain butyne
STEP 2 Number the chain from the double bond
1-butyne
STEP 3 Give the location of each substituent
3-methyl-1-butyne

68. Learning Check Write the IUPAC name for each of the following:
1. CH2=CH─CH2─CH3
2. CH3─CH=CH─CH3
CH3 |
3. CH3─CH=C─CH3
4. CH3─CC─CH3

69. Solution Write the IUPAC name for each of the following:
1. CH2=CH─CH2─CH butene
2. CH3─CH=CH─CH butene
CH3 |
3. CH3─CH=C─CH methyl-2-butene
4. CH3─CC─CH butyne

70. Cis and Trans Isomers In an alkene, cis and trans isomers are possible
because the double bond
Is rigid.
Cannot rotate.
Has groups attached to the carbons of the double bond that are fixed relative to each other.
CH3 CH CH3
CH = CH CH = CH
cis trans CH3

71. Cis-Trans Isomers Cis-trans isomers
Can be modeled by making a “double bond” with your fingers with both thumbs on the same side or opposite from each other.

72. Cis-Trans Isomers
Cis-trans isomers occur when different groups are attached to the double bond.
In a cis isomer, groups on the same side of C=C
In the trans isomer, the groups on opposite sides.

73. Pheromones A pheromone
Is a chemical messenger emitted by insects in tiny quantities.
Called bombykol emitted by the silkworm moth to attract other moths has one trans and one cis double bond.

74. Learning Check
Identify each has having cis or trans groups

75. Solution trans-2-butene Neither cis nor trans 1,1-dichloropropene
cis-1,2-dibromoethene
trans-2-butene
Neither cis nor trans
1,1-dichloropropene
Identical atoms on one C; no cis or trans

76. Hydrogenation In hydrogenation,
Hydrogen atoms add to the carbon atoms of a double bond or triple bond.
A catalyst such as Pt or Ni is used to speed up the reaction.

77. Hydrogenation of Oils Adding H2 to double bonds in vegetable
oils produces
Compounds with higher melting points.
Solids at room temperature such as margarine,
soft margarine,
and shortening.

78. Learning Check
Write an equation for the hydrogenation of 1-butene using a platinum catalyst.

79. Solution Write an equation for the hydrogenation of 1-butene
using a platinum catalyst. Pt
CH2=CH─CH2─CH3 + H2 CH3─CH2─CH2─CH3

80. Trans Fats In vegetable oils, the unsaturated fats usually contain
cis double bonds.
During hydrogenation, some cis double bonds are converted to trans double bonds (more stable) causing a change in the fatty acid structure
If a label states “partially” or “fully hydrogenated”, the fats contain trans fatty acids.

81. Learning Check
(T) True or (F) False
A. ____ There are more unsaturated fats in vegetable oils.
B. ____ Hydrogenation converts some cis-double bonds to
trans- double bonds.
C. ____ Animal fats have more unsaturated fats.

82. Solution (1) True or (2) False
A. T There are more unsaturated fats in vegetable oils.
B. T Hydrogenation of oils converts some cis-double
bonds to trans- double bonds.
C. F Animal fats have more unsaturated fats.

83. Aromatic Compounds Benzene
Has 6 electrons shared equally among the 6 C atoms.
Is also represented as a hexagon with a circle drawn inside.
Cancer causing because so flat
Benzopyrene
Naphthalene
In smoke

84. Common Aromatic Compounds
toluene aniline phenol
(methylbenzene) (benzenamine) (hydroxybenzene)
Trinitrotoluene
TNT

85. Aromatic Compounds in Nature and Health
Vanillin Aspirin
Ibuprofen Acetaminophen
Not Cancer causing because not flat