14.1 Properties of alcohols

Question 1

Aliphatic general formula of alcohols

Answer 1

CnH2n+1OH

Question 2

What is the function group of alcohols

Answer 2

-OH (hydroxyl)

Question 3

Prefix and suffix of alcohols

Answer 3

suffix: —ol
prefix: hydroxy—

Question 4

How do the physical properties of alcohols and alkanes compare? (with same carbon number)

Answer 4

alcohols are:
-less volatile
-higher melting points
-greater water solubility
(differences become smaller as carbon chain increases)

Question 5

How are the differences between alkanes and alcohols physical properties explained?

Answer 5

-alkanes have non-polar bonds because electronegativity of carbon and hydrogen is very similar
-intermolecular forces between non-polar molecules are very weak london forces
-alcohols have a polar O-H bond because of difference in electronegativity of oxygen and hydrogen atoms
-The intermolecular forces will be weak London forces but they will also have hydrogen bonds between the polar O-H groups which are much stronger than London forces

Question 6

Explain the difference between the volatility and boiling points of alkanes and alcohols

Answer 6

-hydrogen bonds hold alcohol molecules together
-requires more energy to break hydrogen bonds than weak london forces in alkanes
-alcohols have a lower volatility (evaporate less easily)

Question 7

Explain the difference in water solubility of alkanes and alcohols

Answer 7

-alkanes are non-polar and cannot form hydrogen bonds with water
-alcohols are soluble as hydrogen bonds form between polar -OH group of alcohol and water molecules

Question 8

Explain the difference in water solubility of alkanes and alcohols

Answer 8

-alkanes are non-polar and cannot form hydrogen bonds with water
-alcohols are soluble as hydrogen bonds form between polar -OH group of alcohol and water molecules

Question 9

What is the effect of the length of hydrocarbon chain on alcohol solubility

Answer 9

-the influence of the -OH group becomes relatively smaller
-solubility decreases
(5 carbons or more = insoluble)

Question 10

What are the three classifications of alcohols?

Answer 10

Primary
Secondary
Tertiary

Question 11

What does the classification of alcohols depend on?

Answer 11

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

Question 12

If there are 2 alcohol groups what is the suffix?

Answer 12

—diol

Question 13

What is a primary alcohol?

Answer 13

The -OH group is attached to a carbon atom that is attracted to one alkyl group and two hydrogen atoms

Question 14

What is a secondary alcohol?

Answer 14

The -OH group is attached to a carbon atom that is attracted to two alkyl groups and one hydrogen atom

Question 15

What is a tertiary alcohol?

Answer 15

The -OH group is attached to a carbon atom that is attracted to three alkyl groups and no hydrogen atoms

Question 16

How do you classify methanol?

Answer 16

Primary alcohol

Question 17

What is the classification of 2-methylpropan-2-ol?

Answer 17

Tertiary

Question 18

What is the classification of propan-2-ol?

Answer 18

Secondary

Question 19

What is the classification of ethanol?

Answer 19

Primary

Question 21

What is the hydroxyl (-OH) group responsible for?

Answer 21

physical and chemical properties

Question 23

What are the properties of methanol?

Answer 23

-Used as a high performance fuel due to efficient combustion
-Useful feedstock, can be converted into polymers, paints, solvents, insulation, adhesives

Question 24

Properties of ethanol

Answer 24

Used in alcoholic drinks, as a fuel, solvent, feedstock

Question 25

Draw hydrogen bonding between two ethanol molecules

Answer 25