Fuels Flashcards
(40 cards)
What are the trends in the fractional distillation column
The shorter the molecules the more flammable
The longer the molecule the less viscous
The shorter the molecule the lower temperature itcondenses at
What is the order of the fractional distillation column from the top down
Gases Petrol Naphtha Kerosene Diesel Fuel oil Bitumen
What is complete combustion
When there’s enough oxygen a hydrocarbon and water are burned to produce carbon dioxide and water
It will burn with a blue flame
The hydrogen and carbon have been oxidised
It happens in gas heaters and the waste products are relatively harmless but lots of energy is released
Methane + oxygen
Carbon dioxide and water
CH4 + 2O2 -> 2H2O + CO2
What is incomplete combustion
When there is not enough oxygen hydrocarbon and oxygen will burn to produce carbon dioxide carbon carbon monoxide and water
It will burn with a yellow flame
What Is bad about carbon
It is soot and leaves behind black sooty marks in the pipes or fire
What is bad about carbon monoxide
It is a colourless odourless and toxic gas because it replaces the oxygen in the red blood cells causing carbon monoxide poisoning
S
4CH4 + 6O2 ->
C + 2CO + CO2 + 8H2O
What makes the best fuel
Easily ignitable
High energy value
Little ash and smoke
Easily stored and transported
What are the negatives of power stations
They burn huge amounts of fossil fuels to create energy
Carbon dioxide and water vapour are released into the atmosphere
Sulphur dioxide is also put into the air
If there’s not enough oxygen soot and carbon monoxide can be released
What is bad about sulfur dioxide
If reacts with clouds to form sulphuric acid which falls as acid rain
What impact does acid rain have
This causes lakes to become acidic and cause cause plant and animal deaths
It kills trees and damages limestone buildings and statues
How can we prevent acid rain
Sulfur can be removed from fuels before they’re burnt
But it costs more and takes more energy
Power stations use acid gas scrubbers to take the harmful gases out before releasing their fumes into the atmosphere eg limestone neutralises the sulfur dioxide
Most cars have catalytic converters
We can reduce the amount of fossil fuels we burn
What effect does carbon dioxide have on the earth
Gases in the atmosphere form an insulating layer around the earth
They absorb the heat that comes from the sun and would usually be sent back out in to space and then reradiate it back to the earth trapping in the heat causing the earth to warm up
How does human activity effect carbon dioxide levels
Deforestation
Carbon dioxide is released when the trees are burned to create land
Microorganisms feed on the dead wood and release CO2
Less CO2 is removed from the atmosphere by photosynthesis
Burning fossil fuels releases locked up carbon into the atmosphere
What is iron seeding
Iron is needed by plants for photosynthesis so injecting iron into the upper ocean promotes the growth of phytoplankton
The blooms absorb carbon dioxide from the atmosphere for photosynthesis
But when the plankton die microorganisms decompose them and use up all of the oxygen which creates dead zones in the ocean
What is biogas
Microorganisms are used to decompose living organisms waste or dead plants to create biogas
What are the uses of biogas
It can be burned to heat water or used in central heating systems or can power a turbine used to generate electricity or can be used as fuel for cars and buses
What are the advantages of biogas
It is renewables so won’t run out the plants which are grown can be easily replaced
It’s carbon neutral because the plants used took in carbon dioxide for photosynthesis when alive
It doesn’t cause acid rain and is quite clean
The raw materials used are cheap and readily available
How is alcohol used as a fuel
It burns to give just co2 and water
It is produced by fermentation of sugar cane or sugar beet
Cars can be adapted to run on 10% ethanol and 90% petrol which is called gasohol
What are the positives of using ethanol as a fuel
Less crude oil is being used up
The crops needed absorb co2 so it is carbon neutral
What are the bad things about using ethanol as a fuel
The crops take up lots of space that could be used to grow foods
The ethanol must be distilled after fermentation which takes up lots of energy
What is a fuel cell
An electrical cell that is supplied with a fuel and oxygen and uses the energy produced to generate electricity
What are the advantages of hydrogen oxygen fuel cells
They’re much more efficient than power stations or batteries
No turbines or generators are needed
There are less stages for energy to be lost through heat
There are no moving parts so energy isn’t lost through friction
There’s no bad pollutants the only waste products are water and heat
