4.2.1 Alcohols

Question 1

What is the functional group of an alcohol?

Answer 1

Hydroxyl group

OH

Question 2

What is the general formula of an alcohol?

Answer 2

Cn H2n+1 OH

Question 3

How do you name alcohols?

one prefix, one suffix

Answer 3

Hydroxyl-
or
-ol

Question 4

What kind of intermolecular forces do alcohols have?

Why?

Answer 4

Hydrogen bonding

Due to the difference in electronegativities in the OH bond

Question 5

How do alcohols’ melting point and boiling point compare to other hydrocarbons’ of similar C chain lengths?
Why?

Answer 5

Higher boiling point that other hydrocarbons

Because they have hydrogen bonding (the strongest type of intermolecular force) , which is stronger than london forces

Question 6

Are alcohols soluble in water?

Why does solubility depend on chain length?

Answer 6

Soluble when short chain
OH bonds to hydrogen to hydrogen bond in water

Insoluble when long chain
Non polarity of C-H bond takes presedence

Question 7

What makes an alcohol primary?

Answer 7

C bonded to OH is only bonded to one other C atom

Question 8

What makes an alcohol tertiary?

Answer 8

C bonded to OH is bonded to three other C atoms

Question 9

Write an equation for the combustion of ethanol

Answer 9

C2H5OH (l) + 3O2 (g) –> 2CO2 (g) + 3H2O

Question 10

What forms if you partially oxidise a primary alcohol

Answer 10

An aldehyde

Question 11

What conditions are needed to partially oxidise a primary alcohol?

Answer 11

Dilute sulphuric acid , potassium dichromate (Vl), distill products as it’s produced, gentle heating

Question 12

Write an equation for the partial oxidation of ethanol

Answer 12

CH3CH2OH (l) + oxidising agent –> CH3CHO (g) + H2O

Question 13

What forms if you fully oxidise a primary alcohol?

Answer 13

A carboxylic acid

Question 14

What conditions are needed to fully oxidise a primary alcohol?

Answer 14

Concentrated sulphuric acid, potassium dichromate (Vl) , heat under reflux

Question 15

Write an equation for the full oxidation of ethanol

Answer 15

CH3CH2OH (l) + 2 oxidising agents –> CH3COOH (g) + H2O (l)

Question 16

What forms if you oxidise a secondary alcohol?

Answer 16

A ketone

Question 17

What conditions are needed for oxidation of a secondary alcohol?

Answer 17

Concentrated sulphuric acid, potassium dichromate (Vl), strong heating

Question 18

Write an equation for the oxidation of propan-2-ol

Answer 18

CH3CH(OH)CH3 (l) + oxidising agent –> CH3COCH3 (g) + H2O (l)

Question 19

Is it possible to oxidise tertiary alcohols?

Answer 19

No

Question 20

What is a dehydration reaction?

Answer 20

A reaction where water is lost to form an organic compound

Question 21

What are the products of dehydration reaction of alcohol?

Answer 21

Alkene and water

Question 22

What are the conditions required for the dehydration of alcohol?

Answer 22

Conc sulfuric acid
or conc phosphoric acid

at 170 degrees

Question 23

What are the products of the halide substitution reaction with alcohol

Answer 23

Haloalkane and water

Question 24

In what form is the halide used in halide substitution reaction?

Answer 24

In the form of hydrogen halide

e.g. HBr

Question 25

How is hydrogen halide made in situ?

Give examples

Answer 25

A salt is reacted with acid to form the hydrogen halide

e.g. sodium bromide reacts with sulfuric acid to form HBr

When iodine is reacted phosphoric acid is used as sulfuric acid oxidizes ions into iodine