Chapter 17 Alcohols and Organic Acids

1
Chapter 17
Alcohols
2
contents

• You will learn about
• Alcohols

3
alcohols
alcohols

• a group of organic compounds with the general
  formula CnH2n1OH, where n is the number of
  carbon atoms in one molecule
• contain the OH functional group of atoms
• names end with ol
• are covalent molecules
• are colourless liquids
• have low boiling points
• are soluble in water

a ball-and-stick model of ethanol, CH3CH2OH
4
alcohols
alcohol homologous series
No. of Carbon Atoms in One Molecule Name Molecular formula Structure of One Molecule Boiling Point (C)
1 Methanol 64
2 78
CH3OH

Ethanol
Ethanol
C2H5OH
5
alcohols
alcohol homologous series
No. of Carbon Atoms in One Molecule Alcohol Member Relative Molecular Mass Structure of One Molecule Boiling Point (C)
3 Propanol (C3H7OH) 60 97
4 Butanol (C4H9OH) 74 117
6
alcohols
reactions of alcohols combustion

• alcohols burn in air to form carbon dioxide and
  water

ethanol oxygen carbon dioxide water
7
alcohols
reactions of alcohols oxidation

• ethanol can also be oxidised by bacteria in air
  to ethanoic acid
• example beer or wine left exposed to the air for
  some days turned sour ethanol oxidised to
  ethanoic acid

ethanol oxygen ethanoic acid water
8
alcohols
ethanol
Ethanol can be made in two ways

• by reacting ethene with steam over a catalyst

• by fermentation of sugars or starch with yeast

9
alcohols
ethanol
To make a sample of ethanol by fermenting sugar
beaker full of water at 37C
conical flask
mixture of yeast and glucose solution
limewater
fermentation of sugar to make ethanol
10
alcohols
uses of ethanol
solvents for paints, varnishes, perfumes
alcoholic drinks
oxidation
ethanol
fuel for vehicles
making ethanoic acid for preserving food and
making esters
11
end of chapter 17 Alcohols