Topic 8: Fuels and Earth Science Flashcards
What is crude oil?
A complex mixture of lots of different hydrocarbons (mostly alkenes)
Is crude oil a finite resource?
Yes
What are hydrocarbons?
Compounds that only contain hydrogen and carbon atoms
What happens as the length of the hydrocarbon chain increases?
Boiling point increases
Viscosity increases
Ease of ignition decreases
What is complete combustion?
A reaction that occurs when a fuel reacts with plenty of oxygen
What is the complete combustion reaction?
Hydrocarbon + oxygen —> carbon dioxide + water
Why are hydrocarbons used as fuels?
When they combust, they release a lot of energy
What is a homologous series?
A family of molecules which have the same general formula and share similar chemical properties e.g. alkanes
What is fractional distillation?
A process used to separate the hydrocarbons in crude oil into fraction according to their boiling points
Each fraction has different uses
How does a fractionating column work?
- Crude oil is heated until most of it has evaporated
- Longer hydrocarbons have higher boiling points so condense near the bottom of the column
- Shorter hydrocarbons have lower boiling points so condense near the top of the column
What are the fractions of crude oil (starting with the fraction produced at the top of the column)?
Gases
Petrol
Kerosene
Diesel oiI
Fuel oil
Bitumen
What are gases used for?
Domestic heating
Cooking
What is petrol used for?
Car fuel
What is kerosene used for?
Aircraft fuel
What is diesel oil used for?
Fuels cars and trains
What is fuel oil used for?
Fuels ships and power stations
What is bitumen used for?
Surfacing roads and roofs
What fractions of crude are non renewable?
Petrol
Kerosene
Diesel oil
What is cracking?
Breaking down long chain, saturated hydrocarbons (alkanes) into shorter, more useful molecules
Why is cracking done?
There is a higher demand for fuels with shorter carbon chains
Shorter hydrocarbons are more useful
What is the equation for cracking?
Long chain alkane —> shorter chain alkane + unsaturated alkene
How is cracking done?
Done by heating the alkane with an aluminium oxide catalyst
What do fossil fuels contain?
Hydrocarbons
Sulphur impurities
What does combustion of fossil fuels release?
Gases and particles which pollute the air
What are the products of incomplete combustion that pollute the air?
Carbon monoxide + Carbon (soot) + Carbon dioxide + Water vapour
When does incomplete combustion of hydrocarbons occur?
When there isn’t enough oxygen for complete combustion to occur
What is the effect of carbon monoxide?
Binds with the haemoglobin in the blood
This causes there to be a lack of oxygen being transported in the body
This can lead to fainting, coma or even death
Properties of carbon monoxide?
Colourless
Scentless
What is the effect of carbon (soot)?
Causes respiratory problems
Reduces air quality
Makes building looks dirty
Where does sulfur dioxide come from?
From when sulfur impurities in fossil fuels react during combustion
What effect does sulfur dioxide have?
Acid rain
This causes damage to trees, statues and buildings
Lakes also become acidic and plants and animals die
Where do oxides of nitrogen come from?
Reactions between nitrogen and oxygen in the air which are caused by the heat of burning fuels e.g. in car engines
What is the effect of oxides of nitrogen?
Acid rain
This causes damage to trees, statues and buildings
Lakes also become acidic and plants and animals die
BECAUSE OXIDES MIX WITH CLOUDS TO FORM ACIDS
What are advantages of hydrogen as a fuel for vehicles?
Very clean - only waste product is water
Obtained from a renewable resource (water), so won’t run out
Can be obtained from the water produced by the cell when used in fuel cells
What are disadvantages of hydrogen as a fuel for vehicles?
Need a special, expensive engine
Hard to store
Manufacturing hydrogen is expensive, often uses energy from fossil fuels
What was the composition of the earths early atmosphere?
Lots of carbon dioxide
Water vapour
Very little oxygen
Some other gases
Why was the earths early atmosphere like this?
Due to volcanic activity that released gases
What happened after the earth cooled?
Water vapour condensed and formed oceans
What did the formation of oceans lead to? Why?
Decrease in CO2 levels
Because CO2 gas dissolved in the oceans
What happened after the oceans formed?
Green, primitive, photosynthesising plants and algae then developed
What did the evolution of green plants lead to? Why?
Decreased CO2 levels
Increased O2 levels
This was due to photosynthesis as photosynthesis absorbs carbon dioxide from the air and produces oxygen
What is the composition of today atmosphere (with the percentages)?
78% nitrogen
21% oxygen
Less than 1% of carbon dioxide, water vapour and noble gases
What is the test for oxygen?
Glowing splint test:
- Glowing split placed into a test tube
- If the splint relights, oxygen gas is present
What are the 3 greenhouse gases?
Carbon dioxide
Water vapour
Methane
What is the greenhouse effect?
When greenhouse gases in the atmosphere absorb long wavelength radiation and re-radiate it in all directions, including back towards Earth, helping to keep the earth warm
What do greenhouses: not absorb, absorb and re-radiate?
Don’t absorb: short wavelength radiation from the sun
Absorb: long wavelength radiation
Re-radiate: long wavelength radiation
How has the increasing human population impacted global warming and climate change?
There’s more greenhouse gas emissions
Why have greenhouse gas emissions increased?
Fossil fuels are being burnt for energy - more CO2 released
Deforestation - less CO2 removed by photosynthesis
Cattle farming - more methane produced
What have increasing levels of greenhouse gases been linked to?
Global warming
What is global warming?
A type of climate change that can cause other types of climate change
What are the consequences of climate change?
Flooding due to melting of polar ice caps causing sea levels to rise
Changing rainfall patterns
What has happened over the years due to greenhouse gases?
Temperature has increased
What are the two ways of reducing CO2 and greenhouse gas emissions?
- Individuals
- Governments
How can individuals reduce carbon dioxide and greenhouse gas emissions?
Walking or cycling instead of driving
Turning down central heating
Eating less meat
How can governments reduce carbon dioxide and greenhouse gas emissions?
Use legislation and financial incentives e.g. congestion charge
Fund research into new energy sources that are renewable and better for the environment
How to remember the fractions of crude oil in order?
Green
Peas
Kill
Diamond
Fusions
Bitch