Chapter 14

Question 1

What is the functional group of alcohols?

Answer 1

-OH, hydroxyl group

Question 2

What is the suffix of alcohols?

Answer 2

-ol

Question 3

What is the general formula of alcohols?

Answer 3

CnH2n+1OH or R-OH

Question 4

When do positional isomers occur in alcohols?

Answer 4

In carbon chains of 3 or more

Question 5

What is a polyhydric alcohol?

Answer 5

Alcohols that contain two or more -OH groups

Question 6

What is the structure of phenol?

Answer 6

When an -OH group is attached directly to a benzene ring

Question 7

What is an ether?

Answer 7

A structural isomer of alcohol

Question 8

Are alcohols polar or non-polar?

Answer 8

Polar

Question 9

Where are the partial charges on an alcohol molecule that cause it to be polar?

Answer 9

• Partial positive charge on the Carbon atom the -OH group is attached to.
• Partial negative charge on the Oxygen in the -OH group.

Question 10

Why does the boiling point increase with chain length in alcohols?

Answer 10

Alcohols create hydrogen bonds with each other, so have higher boiling points than alkanes of similar Mr as more energy is needed to overcome the stronger intermolecular forces.

Question 11

Define volatility?

Answer 11

A measure of the tendency of a substance to vaporise (the higher the boiling point the lower the volatility)

Question 12

How does the volatility of alcohols compare to alkanes?

Answer 12

Alcohols are less volatile than alkanes of similar Mr.

Question 13

What is the solubility of alcohols like?

Answer 13

They have -OH groups which can form hydrogen bonds with water. This makes the first three alcohols soluble in water but after that the long alkyl chain interferes with the Hydrogen bonds.

Question 14

When are alcohols soluble in water?

Answer 14

The first three alcohols are soluble in water but after that the long alkyl chain interferes with the Hydrogen bonds.

Question 15

What is ethanol and when is it used?

Answer 15

Ethanol is ‘alcohol’ in alcoholic drinks. Commonly used as a solvent in the form of methylated spirits.

Question 16

What is methanol and when is it used?

Answer 16

Methanol is used as a petrol additive to improve combustion. Important feedstock in the production of organic chemicals.

Question 17

What is ethane-1,2-diol and when is it used?

Answer 17

Used as antifreeze as it lowers the melting point of water from 0” to as low as -40” when mixed with water.

Question 18

What are the 4 reactions alcohols can take place in?

Answer 18

1. Combustion
2. Oxidation
3. Dehydration
4. Substitution

Question 19

What is produced in the complete combustion of alcohols?

Answer 19

Carbon Dioxide and water

Question 20

Why do alcohols make good fuels?

Answer 20

The combustion of alcohols is exothermic

Question 21

What does increasing the number of carbon atoms in the chain during combustion result in?

Answer 21

It increases the amount of heat energy released per mole.

Question 22

What does the oxidation of alcohols produce?

Answer 22

Molecules with different functional groups

Question 23

What functional group does Aldehydes and Ketones contain?

Answer 23

The CARBONYL GROUP

Question 24

What is the Carbonyl Group ?

Answer 24

A carbon double bonded to the oxygen. -C=O

Question 25

What is the suffix of an Aldehyde?

Answer 25

'...al'

Question 26

What is the suffix of a Ketone?

Answer 26

'...one'

Question 27

What functional group do Carboxylic acids contain?

Answer 27

The CARBOXYL GROUP

Question 28

What is the Carboxyl Group?

Answer 28

-COOH

Question 29

What is the suffix of a Carboxylic Acid?

Answer 29

'....oic acid'

Question 30

What is used to carry out the oxidation of alcohols?

Answer 30

Acidified potassium dichromate (VI) solution

Question 31

What colour does the potassium dichromate solution change to during a reaction?

Answer 31

From orange to green

Question 32

What is the equation for potassium dichromate?

Answer 32

Cr2O7 ^2-

Question 33

What is the equation for the potassium dichromate after it turns green?

Answer 33

Cr ^3+

Question 34

What are primary alcohols oxidised to?

Answer 34

Aldehydes and then to a carboxylic acid

Question 35

How is a primary alcohol oxidised into a aldehyde?

Answer 35

Under distillation with H+/ Cr2O7 ^2-

Question 36

How is a aldehyde oxidised into a carboxylic acid?

Answer 36

Under reflux with H+/Cr2O7 ^2-

Question 37

How are ketones made?

Answer 37

Secondary alcohols are oxidised to ketones, under reflux with H+/Cr2O7 ^2-

Question 38

What are tertiary alcohols oxidised into?

Answer 38

They are not oxidised, the reaction mixture stays orange.

Question 39

Define dehydration?

Answer 39

A water molecule is removed from a starting reactant

Question 40

Define an elimination reaction

Answer 40

A small molecule is removed from a single larger molecule leaving an unsaturated molecule.

Question 41

What acid catalyst is used in the dehydration of alcohols?

Answer 41

Concentrated H2SO4/ Concentrated H3PO4

Question 42

How is a dehydration of alcohols reaction carried out?

Answer 42

The alcohol is heated under reflux in with an acid catalyst

Question 43

What does the dehydration of an unsymmetrical alcohol result in?

Answer 43

2 alkenes that are positional isomers

Question 44

What occurs during the mechanism of the dehydration of alcohols?

Answer 44

The hydrogen atom is removed from the carbon atom bonded to the most number of carbon atoms.

Question 45

Define a substitution reaction

Answer 45

When an atom/ group of atoms is replaced by another atom/ group of atoms.