Transcript Ethanol - Chemistry Crash Course

Ethanol
Chapter 3 CC2
The most common use of ethanol
in industry is as a solvent
Describe one use of ethanol
as a solvent
1 mark
• Ethanol is used as a solvent in antiseptics
because it is able to easily dissolve the
active ingredient and then readily
evaporates from the skin
Relate its solvent properties to
the polarity of the ethanol
molecule
1 mark
• The C-O and O-H bonds are polar
• This leaves a partial negative charge on
the oxygen atom which allows it to easily
dissolve polar substances.
Outline TWO uses of ethanol
as a fuel
2 marks
• Portable fuel in camping stoves (e.g.
methylated spirits)
• Used to modify petrol for use in car
engines
Write an equation for the
fermentation of glucose
1 mark
Describe conditions under which
fermentation is promoted
1 mark
Assess the potential of ethanol
as an alternative fuel. In your
answer you should assess the
impacts and applications of the
chemistry you discuss on the
environment and identify possible
future directions for research
8 marks
Ethanol as a fuel
• Ethanol is not currently viable as an alternative
fuel for mass consumption (1)
• Methods of producing ethanol are expensive
compared to obtaining non-renewable supplies
such as coal and natural gas. However as
supplies of fossil fuels decrease and tax
imposed on using fossil fuels increase and/or
cheaper alternative methods of producing
ethanol are discovered then ethanol may
become more competitive (1)
• Ethanol can be produced by fermentation of
glucose (greener fuel) (1) however
Advantages:(1) takes glucose from naturally
occurring sugar cane and sugar beet. Burning of
this fuel has potential to be greenhouse neutral
(only CO2 removed from the atmosphere by the
plant is returned)
Disadvantages(1)growing of cane occupies large
amounts of land therefore clearing of more land.
Energy inputs which are greenhouse unfriendly
(eg planting, harvesting, burning, distillation).
Also wastes from large fermentation plants are
difficult to dispose of.
Future research could enhance
current technology include (1):
• Improving efficiency of solar powered distillation
processes
• Genetic engineering of bacteria to increase the
concentration of alcohol produced in
fermentation
• Developing mechanisms for the decomposition
of cellulose to produce glucose economically.
New technologies might focus on looking on
alternative pathways to produce ethanol directly
from cellulose
• The most common source of ethanol is
from the addition of water to ethylene. (1)
However (1)
Disdvantage: ethanol obtained by this
method is less efficient than other fuels.
Eg petrol produces more energy per gram
and costs less to extract.
Advantage: of this method produces a
cleaner burn (less soot)