A-Level Chemistry: Alcohols
Ethanol in alcoholic drinks:
In moderation, promotes a feeling of well-being by behaving as a nervous
system depressent (i.e. inteferes with the transmission of nerve impulses).
Larger quantities can lead to loss of balance, poor hand-eye coordination,
inability to judge speed and impaired vision. Can also lead to addiction.
Ethanol is absorbed through the walls of the small intestine and stomach into the
bloodstream. Some remains unchaged and is lost through breath or urine, while
the rest is broken down in the liver. The average human can eliminate about
10cm^3 of ethanol / hour.
Beers: 5%, wines: 12%, spirits (gin, whisky): 40% - these have been
concentrated by distillation.
Ethanol in the industry:
(C2H5OH) is the most important alcohol. Often the solvent in cosmetics like
aftershave and perfumes and used as a fuel and biofuel as well as being used in
alcoholic drinks, methylated spirits.
Used as an intermediate to manufacture drugs, detergents, inks and coatings.
Production of ethanol:
1. Made by hydrating ethene (an addition reaction [addition mechanism]):
reacting ethene (which is made from cracking crude oil fractions) with steam
using sulfuric acid / phosphoric acid as catalyst, 600 degrees celcius and 60
ATM.
A-Level Chemistry: Alcohols 1
, Mechanism for production of ethanol from ethene and steam
2. Made from fermentation: the breakdown of carbohydrates from plants (like
sugarcane and sugar beet) into sugars (glucose) which is broken down to
aqueous ethanol and CO2 by using enzymes from yeast cells in a reaction
called anaerobic respiration:
Rate of reaction is affected by temperature. 35 degrees celcius used: Too
low and the rate of reaction is too slow, too high and the enzymes denature
and can no longer effectively function.
Anaerobic conditions used: To prevent the ethanol produced from being
oxidised to ethanoic acid.
Once fermenting solution contains 15% ethanol, enzymes can no longer
function and the reaction stops. Hence, the process takes place in batches.
Ethanol may be distilled off from the mixture by fractional distillation as its
boiling point (78 celcius) is less than that of water (100 celcius).
Ethanol from fermentation is called a biofuel as it is a fuel produced from a
renewable biological resource.
A-Level Chemistry: Alcohols 2
Ethanol in alcoholic drinks:
In moderation, promotes a feeling of well-being by behaving as a nervous
system depressent (i.e. inteferes with the transmission of nerve impulses).
Larger quantities can lead to loss of balance, poor hand-eye coordination,
inability to judge speed and impaired vision. Can also lead to addiction.
Ethanol is absorbed through the walls of the small intestine and stomach into the
bloodstream. Some remains unchaged and is lost through breath or urine, while
the rest is broken down in the liver. The average human can eliminate about
10cm^3 of ethanol / hour.
Beers: 5%, wines: 12%, spirits (gin, whisky): 40% - these have been
concentrated by distillation.
Ethanol in the industry:
(C2H5OH) is the most important alcohol. Often the solvent in cosmetics like
aftershave and perfumes and used as a fuel and biofuel as well as being used in
alcoholic drinks, methylated spirits.
Used as an intermediate to manufacture drugs, detergents, inks and coatings.
Production of ethanol:
1. Made by hydrating ethene (an addition reaction [addition mechanism]):
reacting ethene (which is made from cracking crude oil fractions) with steam
using sulfuric acid / phosphoric acid as catalyst, 600 degrees celcius and 60
ATM.
A-Level Chemistry: Alcohols 1
, Mechanism for production of ethanol from ethene and steam
2. Made from fermentation: the breakdown of carbohydrates from plants (like
sugarcane and sugar beet) into sugars (glucose) which is broken down to
aqueous ethanol and CO2 by using enzymes from yeast cells in a reaction
called anaerobic respiration:
Rate of reaction is affected by temperature. 35 degrees celcius used: Too
low and the rate of reaction is too slow, too high and the enzymes denature
and can no longer effectively function.
Anaerobic conditions used: To prevent the ethanol produced from being
oxidised to ethanoic acid.
Once fermenting solution contains 15% ethanol, enzymes can no longer
function and the reaction stops. Hence, the process takes place in batches.
Ethanol may be distilled off from the mixture by fractional distillation as its
boiling point (78 celcius) is less than that of water (100 celcius).
Ethanol from fermentation is called a biofuel as it is a fuel produced from a
renewable biological resource.
A-Level Chemistry: Alcohols 2
