GCSE CHEMISTRY - What is Fermentation? - How is Ethanol made on a Large Scale?

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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

glucose ethanol + carbon dioxide
C₆H₁₂O₆_(aq) 2C₂H₅OH_(aq) + 2CO_2(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.

Fermentation 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 and non-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

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