1. C6c Alcohols
Foundation
Ethanol is just one type of alcohol
Molecular Formula: Displayed Formula:
C2H5OH
Higher
Alcohols have the general formula CnH2nOH
You need to be able to use this to:
1. write the molecular formula of an alcohol with up to five carbon atoms
2. draw the displayed formulae of alcohols containing up to five carbon atoms
Methanol Ethanol
Propanol Butanol
Pentanol
2.
3. Making Ethanol by Fermentation
What conditions are needed for fermentation?
1. A glucose and yeast solution are heated at _______oC. This is called the
________________ temperature.
2. No _____________ is present
3. ______________ in the yeast convert glucose into carbon dioxide and ethanol
4. The mixture is ________________ to remove the ethanol
Note that there must be water present (fermentation will not occur with dry glucose
powder and dry yeast)
Higher only
Higher only 3 Very Important Questions
1. Why do we need to use a temperature between 25 oC and 50 oC ?
Too Low =
Too High =
2. Why must there be no oxygen present?
3. What is the advantage of making ethanol in this way?
Uses of Ethanol
• alcoholic beverages;
• solvent (industrial methylated spirits);
• fuel for cars.
4. Making Ethanol by the Hydration of Ethene
• Hydration means ___________________
• Adding water to _______________ produces ethanol
Method
Ethene and steam are passed over a hot ______________ called phosphoric acid
Higher only C2H4 + H2O C2H5OH
What are the advantages and disadvantages of making ethanol by hydration
compared to making it by fermentation ?
Advantages Disadvantages
1. 1.
2. 2.
3. 3.
5. The Dehydration of Ethanol to Ethene
• Adding water to ethene was called _______________
• If we carry out the opposite reaction and remove water from ethanol it is
called ________________________
Method
Ethanol is heated and the vapour is passed over a hot catalyst called “aluminium
oxide” (this is the same method and same catalyst that was used in the catalytic cracking of
ethane)
Higher only
phosphoric acid
hydration
ethene + water ethanol
aluminium oxide
dehydration
