chemical nature of carbon valence electrons? ionic bonding? number of bonds?
TRANSCRIPT
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Uses of HydrocarbonsNumber of
C atomsState Major Uses
1-4 gasheating and cooking fuel
5-7liquids,
(low boiling)solvents, gasoline
6-18 liquids gasoline
12-24 liquidsjet fuel; camp stove fuel
18-50liquids,
(high boiling)
diesel fuel, lubricants, heating oil
50+ solidspetroleum jelly, paraffin wax
1-4 gasheating and cooking fuel
5-7liquids,
(low boiling)solvents, gasoline
6-18 liquids gasoline
12-24 liquidsjet fuel; camp stove fuel
18-50liquids,
(high boiling)
diesel fuel, lubricants, heating oil
50+ solidspetroleum jelly, paraffin wax
Tro, Chemistry: A Molecular Approach 3
Saturated Hydrocarbons
• a saturated hydrocarbon has all C-C single bonds– it is saturated with hydrogens
• saturated aliphatic hydrocarbons are called alkanes
• chain alkanes have the general formula CnH2n+2
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FormulasCH4
C
H
H
H
H
C2H6 CH3CH3 C
H
C
H
H
H
H
H
C3H8 CH3CH2CH3 C
H
C
H
H
H
C
H
H
H
H
C4H10 CH3CH2CH2CH3 C
H
C
H
H
H
C
H
H
C
H
H
H
H
C4H10 C(CH3)2 C
H
C
H
H
H
C
C
H
H
H
H
H
H
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Isomerism• Isomers = different molecules with the same
molecular formula• Structural Isomers = different pattern of atom
attachment
Tro, Chemistry: A Molecular Approach 8
Possible Structural IsomersCarbonContent
MolecularFormula
PossibleIsomers
4 C4H10 25 C5H12 36 C6H14 57 C7H16 98 C8H18 189 C9H20 3510 C10H22 75
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3.4 Naming Alkanes• Compounds are given systematic names by a process that uses
• Follows specific rules– Find parent hydrocarbon chain– Carbons in that main chain are numbered in sequence– Substituents are identified numbered– Write compound name is single word – Name a complex substituents as though it were a compound itself
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Naming Alkanes1) Find the longest continuous carbon chain
2) Number the chain from end closest to a branch– if first branches equal distance use next in
3) Name branches as alkyl groups– locate each branch by preceding its name with the carbon number
on the chain
4) List branches alphabetically– do not count n-, sec-, t-, count iso
5) Use prefix if more than one of same group present– di, tri, tetra, penta, hexa– do not count in alphabetizing
Tro, Chemistry: A Molecular Approach 12
Alkyl GroupsC
C C
C C C
C C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
CH3-, METHYL
CH3CH2-, ETHYL
CH3CH2CH2-, PROPYL
(CH3)2CH-, ISOPROPYL
Tro, Chemistry: A Molecular Approach 13
More Alkyl GroupsC C C C
C C C
C
H
H
H
H
H
H
H
H
H
H
H
H
H
H H
CH3
CH3
CH3
H3C
C C C
CH3H
H
H H
H
H
(CH3)2CHCH2-, ISOBUTYL
CH3CH2(CH3)CH-, sec-BUTYL
CH3CH2CH2CH2-, n-BUTYL
(CH3)3C-, tert-- BUTYL
Tro, Chemistry: A Molecular Approach 14
Drawing Structural Formulas
• draw and number the base chain carbon skeleton
• add the carbon skeletons of each substituent on the appropriate main chain C
• add in required H’s
4-ethyl-2-methylhexane
C C C CC C
C C C
CH3 CH2 CH2 CH3CH CH
CH3 H2C CH3
C C C C C C1 2 3 4 5 6
Tro, Chemistry: A Molecular Approach 15
Reactions of Hydrocarbons
• all hydrocarbons undergo combustion• combustion is always exothermic
– about 90% of U.S. energy generated by combustion2 CH3CH2CH2CH3(g) + 13 O2(g) → 8 CO2(g) + 10 H2O(g)
CH3CH=CHCH3(g) + 6 O2(g) → 4 CO2(g) + 4 H2O(g)
2 CH3CCCH3(g) + 11 O2(g) → 8 CO2(g) + 6 H2O(g)