Making ethanol by fermentation
Ethanol is the alcohol found in beer, wine and spirits. It is also used as a fuel for vehicles, either on its own or mixed with petrol. Ethanol is also used as a solvent. Ethanol is produced by An anaerobic process in which yeast converts sugar to ethanol and carbon dioxide at a warm temperature. and concentrated by The separation of components of a mixture by heating the mixture to form a gas and allowing the difference components to condense at different temperatures.
Fermentation is an Anaerobic processes occur in the absence of oxygen.
glucose 鈫 ethanol + carbon dioxide
Yeast provides the enzymes required for fermentation. The temperature has to be warm but not too warm.
The typical conditions required for fermentation are:
- sugars dissolved in water, mixed with yeast
- anaerobic conditions (no air can get in)
- 25掳C 鈥 35掳C temperature
Fermentation is a slow reaction. It may take days or weeks to finish. It ends when the ethanol concentration reaches about 15%, killing the yeast. If oxygen gets in, the ethanol will oxidise into ethanoic acid and the drink will taste like vinegar.
Question
Describe what happens to the limewater during the experiment shown above.
The limewater changes from colourless to milky. This is because fermentation produces carbon dioxide.
Reactions of alcohols
Methanol is used as a chemical feedstock. It鈥檚 toxic, so it is added to industrial ethanol (methylated spirits) to stop people from drinking it.
Ethanol is the alcohol in beer, wine and spirits. It is also a fuel and a solvent.
Propan-1-ol and propan-2-ol are fuels and solvents.