Use marked Edexcel IAL Chemistry questions to evaluate alternative fuels and transport choices using renewability, carbon dioxide emissions and climate impacts.
Many cars use fuels containing ethanol as well as hydrocarbons. The E numbers of these fuels show the percentage by volume of ethanol in the fuel. For example, an E5 fuel contains 5\% ethanol and 95\% hydrocarbons by volume.
Many countries are gradually replacing E5 fuels with E10 fuels.
Explain how this change might result in a more sustainable fuel.
An answer that makes reference to three of the following points:
- (increased amount of) ethanol used could be bioethanol / ethanol sourced from plants
(1)
- from fermentation (of sugars / glucose using yeast)
(1)
- reducing CO_2 emissions (overall) / (some) CO_2 released in combustion offset by CO_2 used in photosynthesis
(1)
- less impact on global warming / climate change
(1)
- uses less of a finite resource (which can then be used in other processes e.g. manufacture of pharmaceuticals)
(1)
- less pollution from sulfur impurities / less SO_2 emissions
(1)
Allow ethanol can be made from a renewable resource Ignore esterification of vegetable oils (biodiesel)
Allow fermentation is a low energy process
Allow bioethanol is (nearly) carbon neutral / has a lower carbon footprint
Ignore 'crude oil is non-renewable'
Comment - allow reverse arguments in context of E5