Crude oil

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  • Created by: Aleena
  • Created on: 31-12-12 21:20
Crude oil is formed from..
the buried remains of plants and animals
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What is a mixture?
A mixture consists of two or more elements or compounds which aren't chemically bonded.
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Crude oil is a mixture of...
many different compounds. Most of the compounds are hydrocarbon molecules. Most of these hydrocarbons are saturated hydrocarbons called alkanes. The different hydrocarbon molecules arent chemically bonded to each other.
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Can parts of a mixture be seperated out?
Yes
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What is fractional distillation?
Crude oil can be split up into separate fractions with each fraction containing molecules with the same number of carbon atoms to each other. Crude oil is evaporated and then condensed at a number of different temperatures.
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The different fractions of crude oil have different properties due to...
its structure.
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Alkanes are made up of..
chains of carbon atoms surrounded by hydrogen atoms.
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What are the first 4 alkanes are what is different about different alkanes?
Methane, ethane, propane and butane. Different alkanes have chains of different lengths.
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How many bonds do Carbon atoms form?
4
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How many bonds do hydrogen atoms form?
1
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What is the formula of alkanes?
CnH2n+2
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The properties of the hydrocarbons depend on...
the size if their molecules.
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The shorter the molecules the...
more runny ( less viscous) the hydrocarbon is.
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The shorter the molecules the...
more volatile they are (turn into a gas at a lower temperature) so the lower their boiling point.
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The shorter the molecules the...
more flammable the hydrocarbon is.
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Mosrt fuels, such as crude oil and coal contain...
carbon and hydrogen
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During combustion, the Carbon and Hydrogen are oxidised so that...
Carbon dioxide and water vapour are released into the atmosphere.
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What else is produced?
Energy
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Whats the word equation of this?
Hydrocarbon + Oxygen = Carbon dioxide + water vapour
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If the fuel contains sulfur impurities, the sulfur will be released into the atmosphere when the fuel is...
burnt as sulfur dioxide
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Sulfur dioxide causes...
acid rain
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If the fuel burns at a high temperature...
oxides of nitrogen will form
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Oxides of Nitrogen cause...
acid rain
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When thers plenty of oxygen, all the fuels burn. This is called...
complete combustion
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If theres not enough oxygen, some of the fuel doesn't burn. This is called...
partial combustion
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Under these conditions, solid parciles of Soot (carbon) and unburnt fuels are...
released. Carbon Monoxide (poisonous gas) is also released.
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Acid rain causes...
lakes to become acidic and as a result of this many plants and animals die. It aslso kils trees and damages limestone buildings. It also ruins stone statues. Links between acid rain and health problems have been suggested.
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Most of the sulfur can be removed from fuels before they're...
burnt
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Inceasing Carbon Dioxide causes...
climate change
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The level of Carbon dioxide i the atmosphere is increasing becuase of the large amounts of..
fossil fuels humans burn
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This extra Carbon Dioxide has caused the...
average temperature of the Earth to increase- global waming
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What is global warming?
its a type of climate change and causes other types of climate change.
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Scientists have been measuring how much...
sunlight is reaching the surface of the Earth and comparing it to the last 50 years.
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They have found out that in some areas...
nearly 25% less sunlight has been reaching the surface compared to 50 years ago.
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This is called...
global dimming
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Thye think its caused by...
particles of Soot (carbon) and ash that are produced when fossil fuels burnt. These particles reflect sunlight bck into space, or they can help to produce more clouds that reflect the sunlight back into space.
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Biodiesel and Ethanol are ...
biofuel- they will never run out like fossil fuels.
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Ethanol is produced by...
plant material. I
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Its made by...
fermentation of plants
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what is ethanol used for..
to power cars in some plants
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Positives of Ethanol...
The Carbon dioxide released when its burnt was taken in by the plant as it grew, so its Carbon neutral. The only other product is water.
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Negatives of Ethanol...
Engines need to be converted before they'll work with ethanol fuels isnt widely vailable. There are worries that as demands increase farmers will switch from growing food crops to crowing crops from ethanol. This will increase food prices.
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What is Biodiel?
It can be produced from vegetable oils. I
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Positives of Biodiesel...
is carbon neutral. Engines dont need to be converted. It produces less sulfur dioxide than ordinary petrol and diesle
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Negatives of biodiesle...
Cant make enough to completely replace diesel. Expensive to make. Could increase food prices.
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Long chain hydrocarbons arent that useful because...
they from thick gloopy liquids
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What is cracking?
The process that turn the longer molecules produced by fractional distillation are turned into smaller ones.
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What products does cracking make?
fuels e.g petrol for cars and paraffin for jet fuel. It also produces substances like ethene which are needed for making plastics. Diesel (long molecule) makes these 3 smaller molecules.
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What type of reaction is cracking?
Thermal decomposition- breaking down molecules by heating them.
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The first step is to..
heat the long-chain hydrocarbons to vaporise it (turn it into a gas)
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Then the vapour is...
passed over a catalyst at a high temperature (400-too degrees Celsius) or mixed with steam art a very high temperature
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Most of the products of cracking are...
alkanes and unsaturated hydocarbon (alkenes)
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What are alkenes?
hydrocarbons which have a double bond between two of the Carbon atoms in their chain. They're unsaturates (can mke more bonds)- double bond can open up allowing the two carbon atoms to bond with other atoms.
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The formula of alkenes are...
CnH2n
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How do you test fro an alkene?
Add the substance to bromine water. An alkene will decolourise the bromine water, turning it from orange to colourless. This is because the double bond has opened up and formed bonds with the bromine.
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What is Ethen reacted with to produce Ethanol?
Thene can be hydrated with steam in the presence of a catalyst to make ethanol.
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Positives of this process?
Its a cheap process at the moment becuase ethen is quite cheap and not much of it is wasted.
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Ethanol can also be produced from...
renewable resources
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alcohol isnt made from..
ethene
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its made from...
fermentation
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The raw material for fermentation is sugar. This is converted into ethanol using yeast. What is the word equation for this?
Sugar = Carbon dioxide + ethanol
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This process needs a lower temperature and simpler equipment than when using ethene. This saves,,,
energy so is less expensive.
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Another advantaghe is...
that sugar is a renewable resource. Its grown as a major crop in poor countries all over the world.
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What is the advantage of ethanol produced this way?
It can be used as a cheap fuel in countries which dont have oil reserves for petrol.
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What is the disadvantage of etanol produced this way?
The ethanol you get from this process isnt very concentrated, so if you wanted to increase is concentration you would have to distil it. It also needs purifying
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Alkenes can be used to make..
polymers
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What is polymerisation?
The joining together of lots of small alkene molecules (monomers) to form very large molecules (polymers)
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The differnt polymers have different...
physical properties. The physical properties depend what its made from, the temperature and pressure pf polymerisation.
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The physical properties make tthem suitable for...
various different uses.
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New uses are being developed all the time. For example...
waterproof coatings for fabrics, dental polymers are used in tooth fillings, wound dressings which keep wounds moist. New biodegradable packaging materials are made from polymers
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Smart materails are made from polymers. What is a smart material?
Its a polymer taht getss softer as it gets warmer. Memory foam is an example of a smart material Mattresses can be made from memory foam- they mould to your body shape when you lie in them.
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Advantage of polymers is..
they're cheap
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Disadvantage of polymers...
Most are biodegradable- they're not broken down by microoraganisms so they don't rot.
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Therefore they're difficult to get rid of. For example if you bury them at a landfuill site, tehy'll...
still be there years later.
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The best thing to do with polymers is to...
reuse them as much as possible and then recycle them if you can.
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Products from polymers are usually...
cheaper than products made from metals.
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However, as crude oil resources get used up,the price of crude oil will...
rise
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Card 5

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