ethanol C2H4(g) + H2O(l)
C2H5OH(l)gcsescience.com 42 gcsescience.com
Making Ethanol.
What is Ethanol?
Ethanol is an alcohol with the molecular formula C2H5OH
(see also the
structural
formula).
Ethanol is not a hydrocarbon because the molecule
contains oxygen as well as hydrogen and carbon.
Ethanol is a colourless
liquid which boils at
78 °C.
It is completely miscible with water.
This means that it mixes with water
in any quantity.
Ethanol is a neutral liquid.
How can Ethanol be Made?
Ethanol can be made
by the fermentation
of a sugar
solution (in a batch
process)
or
by the reaction of ethene with steam in the presence
of phosphoric acid
(in a continuous process, see below).
What is a Continuous Process?
A continuous process means that
reactants are
constantly being
put in at one
end of the reaction vessel and
products
are
constantly being taken out at the
other end of the reaction
vessel.
Adding the components of water across the double bond
of ethene is
called the hydration of ethene.
The reaction
is carried out at a
high temperature and a high pressure.
ethene
+ steam
ethanol
C2H4(g)
+ H2O(l)
C2H5OH(l)
See a comparison of the batch
process
with the continuous process below.
| Process | Reaction | Renewable Resource? | Rate of Reaction | Product |
| Batch Process | Fermentation | Yes - Sugar Cane | Slow | Ethanol / Water mixture |
| Continuous Process | Hydration of Ethene | No - Crude Oil | Fast | Pure Ethanol |
Industry would rather use a continuous process than
a batch process
because of the fast production of a
pure product. In some countries it may be more
practical to use a batch process - see the next page.
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