Upload
sheryl-freeman
View
213
Download
1
Embed Size (px)
Citation preview
C1b Topic 7 Internal Assessment:
Fuels
What makes a good fuel?• Energy value: e.g. kJ of heat energy released per kg; • Availability: Geographical convenience, oil production
levels; • Storage: Health and safety issues e.g. coal very safe,
natural gas more dangerous • Cost: Extraction, transport, market price • Toxicity and Pollution: Greenhouse effect (which produces
the least or most CO2/energy released?); sulphur content of fuel (most removed before fuel used to minimise sulphur dioxide and acid rain formation); efficiency of combustion e.g. minimum carbon monoxide and soot levels
• Ease of use: Transferred easily
Combustion
• Combustion can be either complete or incomplete
– Complete combustion = plenty of oxygen available; carbon dioxide and water produced; blue flame
– Incomplete combustion = not much oxygen present; carbon monoxide (toxic), carbon (black soot), carbon dioxide and water produced; yellow flame
Word Equations – when done, convert to balanced symbol equations
a) Methane + oxygen →
Methane = CH4
b) Ethane + oxygen →
Ethane = C2H6
c) Ethanol + oxygen →
Ethanol = C2H5OH
d) Butanol + limited oxygen →
Butanol = C4H9OH
Alternative Fuels
• Most of our fuel used today comes from crude oil– Examples: petrol, diesel, kerosine etc.
• Are these fuels renewable or non-renewable?– What is meant by these terms?
• What are some alternative fuels that could be used?
Some Alternative Fuels
Biodiesel and Bioethanol: liquid fuels made fromplant material and recycled elements of the food chain. Toa large extent, they are renewable and sustainable.Biodiesel is a diesel alternative. Bioethanol is a petroladditive/substitute. They are produced from crops such ascereals, oilseeds, and sugar beet.• What advantages/disadvantages do biofuels have over
oil?
Hydrogen: can be obtained by the
electrolysis of water (so a bountiful supply!).
Also, when hydrogen burns a lot of energy is
released and is completely pollution-free
(the only product is water).
• Hydrogen powered buses produce no pollution from their exhausts, but using hydrogen is not a completely pollution-free option at the moment. Explain why.
How Science Works
• Reliable – data can be reproduced by others (in same conditions)
• Accurate – precise or correct in all details• Valid – data is reliable AND answers the
original questions• Fair Testing – controlling as many
variables as possible• Bias – opinion that strongly favours one
side in preference to another
• Think about why things might be biased– People who want to make a point can
sometimes present data in a biased way to suit their own purposes
– Example: companies may want to ‘big up’ their products (especially more expensive ones) to make a quick profit
Example: Do power lines cause cancer?
• Scientists desire to study the link between the presence of power lines and incidence of cancer in children
• Design a study that the scientists could perform. Use ideas of validity, fair testing, accuracy, and reliability when designing your study.