14.1 Properties of alcohols Flashcards

1
Q

What functional group do alcohols contain

A

-OH

Hydroxyl group

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2
Q

What is the hydroxyl group responsible for

A

Both the physical and chemical properties of the alcohols

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3
Q

What is methanol used for

A

Simplest alcohol
High-performance fuel - efficient combustion
Important chemical feedstock - starting chemical in many syntheses, polymers, paints, solvents, insulation

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4
Q

What is ethanol used in

A

Alcoholic drinks

Fuel

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5
Q

Naming alcohols

A

Adding -ol to stem name of longest carbon chain

Position of functional group indicated using number

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6
Q

Differences in physical properties between alcohols and alkanes of the same number of carbon atoms

A

Alcohols less volatile, have higher melting points and greater water solubility than alkanes

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7
Q

How can the differences in physical properties between alcohols and alkanes of the same number of carbon atoms be explained

A

Alkanes - non-polar bonds as electronegativity of H and C very similar
Intermolecular forces between non-polar molecules are very weak London forces
Alcohols have polar O-H bond due to difference in electronegativity of O and H atoms
Intermolecular forces very weak London forces but also much stronger hydrogen bonds between polar O-H groups

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8
Q

What must happen for a liquid alcohol to be changed into a gas

A

Intermolecular hydrogen bonds must be broken
Requires more energy than overcoming London forces in alkanes
Alcohols therefore lower volatility than alkanes

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9
Q

What word is used to describe compounds with low boiling points

A

Volatile

The higher the boiling point, the lower the volatility

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10
Q

Are alkanes and alcohols soluble in water

A

Alkanes are non-polar and cannot form H bonds with water

Alcohols are completely soluble in water as H bonds form between polar -OH group and water molecules

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11
Q

How does the influence of the -OH group change as a hydrocarbon chain increases in size

A

The influence decreases

Solubility of longer chain alcohols decreases

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12
Q

How can alcohols be classified

A

As primary, secondary or tertiary

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13
Q

What does the classification of alcohols depend on

A

The number of hydrogen atoms and alkyl groups attached to the carbon atom that contains the alcohol functional group

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14
Q

How is the -OH attached in a primary alcohol

A

Attached to a carbon atom that is attached to two H atoms and one alkyl group

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15
Q

How is the -OH attached in a secondary alcohol

A

Attached to a carbon atom that is attached to one H atom and two alkyl groups

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16
Q

How is the -OH attached in a tertiary alcohol

A

Attached to a carbon atom that is attached to NO H atoms and three alkyl groups