Alcohol

Question 1

Physical properties

Answer 1

Less volatile than alkanes
Higher melting points
Greater water solubility than alkanes

Question 2

Why are alcohols soluble in water

Answer 2

Polar OH bond, different electronegativities

Hydrogen bonds form between water and hydroxyl group on the end

Question 3

Why do alcohols have a fairly low boiling point

Answer 3

Hydrogen bonds broken to become a gas

More force needed to break them

Question 4

Solubility of alcohols

Answer 4

Hydroxyl and water molecules form hydrogen bonds

Hydrocarbon chain increases in size, hydroxyl influence decreases, solubility decreases

Question 5

Combustion of alcohols

Answer 5

Exothermic

As number of C increases, quantity of heat released/ mole increases

Question 6

Oxidation of alcohols

Answer 6

Oxidised by K2Cr2O7, acidified by H2SO4
Dichromate (6), orange
Chromium (3) ions, green

Question 7

Primary alcohol oxidation

Answer 7

Distillation, acidified potassium dichromate, aldehyde

Reflux, acidified potassium dichromate, carboxylic acid

Question 8

Oxidation of secondary alcohols

Answer 8

Reflux, acidified potassium dichromate, ketone

Question 9

Oxidation of tertiary alcohols

Answer 9

Do not oxidise

Question 10

Dehydration of alcohols

Answer 10

Water is removed from starting material
Reflux, acid catalyst, gives alkene
Elimination

Question 11

Substitution reactions of alcohols

Answer 11

Alcohol and HX => haloalkane
Reflux, sulphuric acid and sodium halide
Release water