1. Chapter 24 Organic Chemistry
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Hydrocarbons
Carbon has 4 valence electrons, and therefore forms 4 bonds.
4 single bonds; tetrahedral; sp3 hybridized
1 double and 2 single bonds; trigonal planar; sp2 hybridized
1 triple and 1 single, or 2 double bonds; linear; sp hybridized
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4. What is the geometry around the bottom carbon atom in acetonitrile?
A. Octahedral
B. Trigonal planar
C. Linear
D. Tetrahedral
Answer: D

5. Stability of Organic Substances
Carbon has an exceptional ability to bond to itself
C-H and C-C bond are non-polar
C-O and O-H bonds are very polar
Often the reactivity or other properties of an organic molecule are determined by the presence of functional groups.
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6. C-H
C-C
C=N
C-H and C-C
Answer: C

7. Polar Solvents Nonpolar Solvents
Change in solubility:
Polar Solvents Nonpolar Solvents
A.Increase Increase
B.Increase Decrease
C.Decrease Increase
D.Decrease Decrease
Answer: C

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Hydrocarbons
There are four basic types of hydrocarbons:
Alkanes
Alkenes
Alkynes
Aromatic hydrocarbons
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Alkanes
Alkanes contain only single bonds.
They are also known as saturated hydrocarbons.
They are “saturated” with hydrogens.
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Formulas
Lewis structures of alkanes look like this
They are also called structural formulas.
They are often not convenient, though, so more often condensed formulas are used.
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Properties of Alkanes
The only van der Waals force is the London dispersion force.
The boiling point increases with the length of the chain.
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12. Two C-H bonds and one C-C bond Two C-H bonds and two C-C bonds
Three C-H bonds and one C-C bond
Four C-H bonds and two C-C bonds
Answer: B

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Structure of Alkanes
Carbons in alkanes are sp3 hybrids.
They have a tetrahedral geometry and  bond angles.
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Structure of Alkanes
There are only -bonds in alkanes.
There is free rotation about the C—C bonds.
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Isomers
Isomers have the same molecular formulas, but the atoms are bonded in a different order.
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16. Lewis structures of isomers are different and this proves that isomers have different physical and chemical properties.
Each isomer of a hydrocarbon molecule has a different number of C-H bonds and therefore the isomers have different physical and chemical properties.
Melting and boiling points can be significantly different as shown in Table 24.3 of text.
All of the above
Answer: C

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Organic Nomenclature
There are three parts to a compound name:
Base: This tells how many carbons are in the longest continuous chain.
Suffix: This tells what type of compound it is.
Prefix: This tells what groups are attached to the chain.
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How to Name a Compound
Find the longest chain in the molecule.
Number the chain from the end nearest the first substituent encountered.
List the substituents as a prefix along with the number(s) of the carbon(s) to which they are attached.
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How to Name a Compound
If there is more than one type of substituent in the molecule, list them alphabetically.
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20. Sample Exercise 24.1 Naming Alkanes
Give the systematic name for the following alkane:
Practice Exercise
Name the following alkane:

21. Sample Exercise 24.2 Writing Condensed Structural Formulas
Write the condensed structural formula for 3-ethyl-2-methylpentane.
Practice Exercise
Write the condensed structural formula for 2,3-dimethylhexane. 21

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Cycloalkanes
Carbon can also form ringed structures.
Five- and six-membered rings are most stable.
They can take on conformations in which their bond angles are very close to the tetrahedral angle.
Smaller rings are quite strained.
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23. A. CnH2n–2
B. CnH2n–1
C. CnH2n
D. CnH2n+1
Answer: C

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Alkenes
Alkenes contain at least one carbon–carbon double bond.
They are unsaturated.
That is, they have fewer than the maximum number of hydrogens.
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Structure of Alkenes
Unlike alkanes, alkenes cannot rotate freely about the double bond.
The side-to-side overlap in the -bond makes this impossible without breaking the -bond.
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Structure of Alkenes
This creates geometric isomers, which differ from each other in the spatial arrangement of groups about the double bond.
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Structure of Alkenes
Structure also affects the physical properties of alkenes.
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28. Answer: A
A. 1
B. 2
C. 3
D. 4

29. One
Two
Three
Four
Answer: B

30. Practice Exercise Sample Exercise 24.3 Drawing Isomers
Draw all the structural and geometric isomers of pentene, C5H10, that have an unbranched hydrocarbon chain.
Practice Exercise
How many straight-chain isomers are there of hexene, C6H12? 30

31. Nomenclature of Alkenes
The chain is numbered so the double bond gets the smallest possible number.
cis-Alkenes have the carbons in the chain on the same side of the molecule.
trans-Alkenes have the carbons in the chain on opposite sides of the molecule.
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Alkynes
Alkynes contain at least one carbon–carbon triple bond.
The carbons in the triple bond are sp-hybridized and have a linear geometry.
They are also unsaturated.
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33. Nomenclature of Alkynes
4-methyl-2-pentyne
The method for naming alkynes is analogous to the naming of alkenes.
However, the suffix is -yne rather than -ene.
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34. Practice Exercise Sample Exercise 24.4 Naming Unsaturated Hydrocarbons
Name the following compounds:
Practice Exercise
Draw the condensed structural formula for 4-methyl-2-pentyne. 34

35. Aromatic Hydrocarbons
Aromatic hydrocarbons are cyclic hydrocarbons that have some particular features.
There is a p-orbital on each atom.
The molecule is planar.
There is an odd number of electron pairs in the -system.
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36. Aromatic Nomenclature
Many aromatic hydrocarbons are known by their common names.
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37. Structure of Aromatic Compounds
Two substituents on a benzene ring could have three possible relationships:
ortho-: On adjacent carbons.
meta-: With one carbon between them.
para-: On opposite sides of ring.
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Functional Groups
The term functional group is used to refer to parts of organic molecules where reactions tend to occur.
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Alcohols
Alcohols contain one or more hydroxyl groups, —OH.
They are named from the parent hydrocarbon; the suffix is changed to -ol and a number designates the carbon to which the hydroxyl is attached.
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Alcohols
Alcohols are much more acidic than hydrocarbons.
pKa ~15 for most alcohols.
Aromatic alcohols have pKa ~10.
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Ethers
Ethers tend to be quite unreactive.
Therefore, they are good polar solvents.
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Aldehydes
In an aldehyde, at least one hydrogen is attached to the carbonyl carbon.
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Ketones
In ketones, there are two carbons bonded to the carbonyl carbon.
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Carboxylic Acids
Acids have a hydroxyl group bonded to the carbonyl group.
They are tart tasting.
Carboxylic acids are weak acids.
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45. A. Lactic acid and formic acid B. Citric acid and ethanoic acid
C. Ethanoic acid and benzoic acid
D. Lactic acid and citric acid
Answer: D

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Esters
Esters are the products of reactions between carboxylic acids and alcohols.
They are found in many fruits and perfumes.
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47. Sample Exercise 24.6 Naming Esters and Predicting Hydrolysis Products
In a basic aqueous solution, esters react with hydroxide ion to form the salt of the carboxylic acid and the alcohol from which the ester is constituted. Name each of the following esters, and indicate the products of their reaction with aqueous base.
Practice Exercise
Write the condensed structural formula for the ester formed from propyl alcohol and propionic acid. 47

48. A. Presence of C-O-C bond. B. Long hydrocarbon chains
C. Presence of ester linkage
D. Presence of C=O group
Answer: B

49. Answer: C
A. Solubility of phospholipids in water increases with greater size and mass of multiple layers.
B. Solubility of phospholipids in water increases with length of hydrophobic region.
C. Hydrophobic tails (nonpolar) mutually interact with one another and hydrophilic heads (polar) interact with water.
D. Hydrophilic tails (nonpolar) mutually interact with one another and hydrophobic heads (polar) interact with water.

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Amides
Amides are formed by the reaction of carboxylic acids with amines.
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Amines
Amines are organic bases.
They generally have strong, unpleasant odors.
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