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

CnH2n+1OH

Question 3

How do you name alcohols?

Answer 3

Hydroxyl-
OR
-ol

Question 4

What kind of intermolecular forces do alcohols have? Why?

Answer 4

Hydrogen bonding, due to the electronegativity difference in the OH bond.

Question 5

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

Answer 5

Higher because they have hydrogen bonding —> 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 hydrogen bonds to hydrogen bond in water
Insoluble when long chain — non-polarity of C-H bond takes precedence

Question 7

What makes a primary alcohol?

Answer 7

C bonded to OH is only bonded to 1 other C atom.

Question 8

Write an equation for the combustion of ethanol.

Answer 8

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

Question 9

What forms if you partially oxidise a primary alcohol?

Answer 9

An aldehyde

Question 10

What conditions are needed to partially oxidise a primary alcohol?

Answer 10

Dilute sulphuric acid, potassium dichromate (VI), distill product as it’s produced, gentle heating.

Question 11

Write an equation for the partial oxidation of ethanol.

Answer 11

CH3CH2OH (l) + [O] —> CH3CHO (g) + H2O (l)

Question 12

What forms if you fully oxidise a primary alcohol?

Answer 12

A carboxylic acid

Question 13

What conditions are needed to fully oxidise a primary alcohol?

Answer 13

Concentrated sulphuric acid, potassium dichromate (VI), reflux, strong heating

Question 14

Write an equation for the full oxidation of ethanol

Answer 14

CH3CH2OH (l) + 2[O] —> CH3COOH (g) + H2O (l)

Question 15

What forms if you oxidise a secondary alcohol?

Answer 15

A ketone

Question 16

What conditions are needed for the oxidation of a secondary alcohol?

Answer 16

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

Question 17

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

Answer 17

CH3CH(OH)CH3 (l) +[O] —> CH3COCH3 + H2O (l)

Question 18

Is it possible to oxidise a tertiary alcohol?

Answer 18

No

Question 19

What is a dehydration reaction?

Answer 19

A reaction where water is lost to form an organic compound.

Question 20

What are the products of dehydration reaction of alcohol?

Answer 20

Alkene and water

Question 21

What are the conditions required for dehydration of alcohol?

Answer 21

Concentrated sulphuric acid or concentrated phosphoric acid and 170 degrees Celsius

Question 22

What are the products of the halide substitution reaction with alcohol?

Answer 22

Haloalkane and water

Question 23

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

Answer 23

In the form of hydrogen halide, e.g. HBr

Question 24

How is hydrogen halide made in situ? Give examples.

Answer 24

A salt is reacted with acid to form the hydrogen halide.
E.g. sodium bromide reacts with sulphuric acid to form HBr
When iodine is reacted phosphoric acid is used as sulphuric acid oxidises iodide ions into iodine