3.5 Alcohols
3.3.5.1 Alcohol production
Explain the meaning of the term biofuel.
Justify the conditions used in the production of ethanol by fermentation of
glucose.
Write equations to support the statement that ethanol produced by
fermentation is a carbon neutral fuel and give reasons why this statement
is not valid.
Outline the mechanism for the formation of an alcohol by the reaction of
an alkene with steam in the presence of an acid catalyst.
Discuss the environmental (including ethical) issues linked to decision
making about biofuel use.
Alcohols contain an -OH group and follow the general formula C nH2n+1OH
Industrial production of alcohols via Fermentation:
Fermentation is an exothermic process, carried out by yeast in anaerobic
conditions. Yeast produces enzymes which converts sugars, such as glucose, into
ethanol and carbon dioxide. The enzyme works at an optimum temperature of
30-40oC. If it’s too cold the reaction is slow and if its too hot the enzyme is
denatured.
When the solution reaches 15% ethanol, yeast dies. Fractional distillation is used
to increase concentration of ethanol. Fermentation uses cheap equipment and
renewable sources, but the ethanol produced by this has to be purified.
Industrial production of alcohols via Hydration:
This method produces alcohols from alkenes in the presence of an acid catalyst.
Phosphoric acid is commonly used as the catalyst under aqueous conditions at
300oC and high pressures.
This method produces alcohols from alkenes in the presence of an acid catalyst.
Phosphoric acid is commonly used as the catalyst under aqueous conditions at
300oC and high pressures.
3.3.5.1 Alcohol production
Explain the meaning of the term biofuel.
Justify the conditions used in the production of ethanol by fermentation of
glucose.
Write equations to support the statement that ethanol produced by
fermentation is a carbon neutral fuel and give reasons why this statement
is not valid.
Outline the mechanism for the formation of an alcohol by the reaction of
an alkene with steam in the presence of an acid catalyst.
Discuss the environmental (including ethical) issues linked to decision
making about biofuel use.
Alcohols contain an -OH group and follow the general formula C nH2n+1OH
Industrial production of alcohols via Fermentation:
Fermentation is an exothermic process, carried out by yeast in anaerobic
conditions. Yeast produces enzymes which converts sugars, such as glucose, into
ethanol and carbon dioxide. The enzyme works at an optimum temperature of
30-40oC. If it’s too cold the reaction is slow and if its too hot the enzyme is
denatured.
When the solution reaches 15% ethanol, yeast dies. Fractional distillation is used
to increase concentration of ethanol. Fermentation uses cheap equipment and
renewable sources, but the ethanol produced by this has to be purified.
Industrial production of alcohols via Hydration:
This method produces alcohols from alkenes in the presence of an acid catalyst.
Phosphoric acid is commonly used as the catalyst under aqueous conditions at
300oC and high pressures.
This method produces alcohols from alkenes in the presence of an acid catalyst.
Phosphoric acid is commonly used as the catalyst under aqueous conditions at
300oC and high pressures.
