gcsescience.com 18 gcsescience.com
Rates of Reaction
Enzymes - Yeast - Fermentation - Alcohol.
What is Fermentation?
Fermentation is the name given to the process
where a sugar (glucose) solution containing yeast
is turned into alcohol (ethanol).
The balanced equation for fermentation is
ethanol + carbon dioxide
C6H12O6(aq) 2C2H5OH(aq) + 2CO2(g)
The carbon dioxide gas bubbles out
of the solution
into the air leaving a mixture of ethanol and water.
Fermentation must be carried out in the absence of air to
make ethanol. This is called anaerobic conditions.
If air is present, ethanoic acid is made instead of ethanol.
will not happen without yeast.
Yeast is a microorganism containing an enzyme
which acts as a catalyst. Fermentation works
best in warm conditions (between 18 and 35 °C)
and at a neutral or acidic pH (between 4 and 7).
See some other examples of fermentation.
How is Ethanol made on a Large Scale?
Ethanol is made from both renewable
resources. Ethanol can be made on a large scale for use as a
fuel or solvent by the hydration of ethene (non-renewable)
or by the fermentation (see above) of sugar cane (renewable).
Fermentation is the method used to make alcoholic drinks.
What does Renewable mean?
Renewable means that the resource can be replaced.
For example more sugar cane can be grown
for fermentation. Compare this with using fossil fuels
which are the non-renewable source of ethene.
Links Catalysts and Energy Enzymes Revision Questions
gcsescience.com The Periodic Table Index Fermentation Quiz gcsescience.com
Home GCSE Chemistry GCSE Physics
Copyright © 2015 gcsescience.com. All Rights Reserved.