Crude oil is oil in its original form, which comes from underground and at the bottom of the sea. It is thick, black, sticky and has a strong smell.
Disadvantages of Ethanol
Disadvantages of using ethanol as a fuel:
- It costs money to convert the engine
- More sugar needs to be grown to meet demand
- Sugar is likely to increase in price
- It can be a health risk when burnt
- It produces less energy than petrol when burnt
Social impact of polymers
- Fewer trees are cut down if people use plastic instead of wood
- They have many different uses according to their properties
- They are cheap to make
- Jobs are provided in companies which manufacture polymers
- Landfills, where waste polymers go, are ugly
- They give off toxic fumes when burnt
- People don't like living near factories where they are made
- They can look cheap compared to natural resources
Advantages of Biofuels
- They tackle global warming by taking carbon dioxide from the air
- It doesn't take much to convert engines
- They make little contribution to the greenhouse effect
- They provide jobs in local areas
- Use of fossil fuels are reduced
- They are biodegradable
- They are non toxic
- They can be used in any diesel vehicle
Examples of Alkanes
Methane - CH4
Ethane - C2H6
Propane - C3H8
Butane - C4H10
Ethanol is the scientific word for alcohol. It is useful as vehicle fuel whern mixed with petrol, and is extracted by fermentation. This converts sugar from sugar cane or sugar beat into ethanol and carbon dioxide. Yeast is used because it contains enzymes which speed up the process. The formula is:
C6H12O6 ------------------> 2C2H5OH + 2CO2
(glucose) (yeast enzymes) (ethanol) (carbon dioxide)
Hydrocarbons can be tested using yellow-brown bromine water to see whether they are alkanes or alkenes.
Alkanes: Bromine water stays yellow-brown
Alkenes: Bromine water turns colourless like water
Polymers are lots of monomers linked together - the double bonds of monomers can be opened up and linked to a diffrerent monomer, creating polymers.
Structure of emulsifiers
Hydrogenation Part 1
1. Vegetable oils are liquid at room temperature. They are unsaturated, have double bonds and a low melting/boiling point.
2. There are weak forces between the molecules because of big gaps.
3. Hydrogen is added and the melting/boiling points increase.
4. Some or all of the double bonds are replaced with single bonds when hydrogen is added, at 60C over a nickel catalyst, which speeds up the reaction. This process is called hydrogenation.
Hydrogenation Part 2
5. The molecules now fit together better. There are smaller gaps between them and therefore stronger forces. The melting point is higher.
6. Because of the higher meliting point, the vegetable oils are solid at room temperature.
7. This process is called 'hardening' vegetable oils.
8. The vegetable oils are now called 'hydrogenated' oils. They can be used in bread, cakes, biscuits and pastry.
Role of emulsifiers
The role of an emulsifier is to prevent an emulsion (a mixture of oil and water) from separating.
Disadvantages of Hydrogen
*Disadvantages of using hydrogen as fuel:
- It is expensive to produce from electricity
- It is difficult to store safely
An example of Cracking
Cracking Decane using thermal decomposition:
C10H22 ------> C5H12 + C3H6 + C2H4
(decane) (pentane) (propene) (ethene)
Burning when there is plenty of oxygen:
Hydrocarbon + oxygen ---> carbon dioxide + water
Particulates from burning fossil fuels
Big molecules of hydrocarbons react with oxygen and do not always burn completely. Particles of carbon and unburnt hydrocarbons are produced - particulates.
They can damage lung cells and may cause cancer, as well as having an effect towards global dimming.
Acid rain from burning fossil fuels
- Trees are damaged/killed
- pH of lakes and rivers is changed, which the fish cannot tolerate
- Metals are leached into rivers, poisoning fish
- Buildings/structures are attacked and worn away
Crabon monoxide from burning fossil fuels
When there is not enough oxygen in the engine cylinders, incomplete combustion produces carbon monoxide.
It is poisonous, and our red blood cells carry it round the body instead of oxygen, causing serious harm.
Nitrogen oxides from burning fossil fuels.
The hign temperature of an engine means that the nitrogen and oxygen in the air react together, producing nitrogen oxides.
They are poisonous and trigger some people's asthma, as well as contributing to acid rain.
Carbon dioxide from burning fossil fuels
- It collects in the atmosphere and reduces the amount of heat lost by the earth
- The temperature of the earth rises and melts the ice caps
- There is a rise in sea levels and widespread flooding
Sulphur dioxide from burning fossil fuels
Impurities of sulphur react with oxygen when they burn, producing sulphur dioxide.
It is poisonous and acidic, which means it causes engine corrosion and acid rain.
Alkanes have single bonds and are saturated, which means every bond is used to link to a different atom.
For example: A plug
Thermosetting plastics cannot be recycled. They do not go soft or melt when heated. Instead they char, because they have chemical bonds AND intermolecular forces between the polymer molecules. The chemical bonds are strong and do not break when heated.
Pressing of vegetable oils
For example: olive oil
1. Olives are collected and crushed.
2. Water is added and the mixture is stirred.
3. The mixture is pressed to extract the oil.
4. The oil separated from the water and is collected.
In a cracker a fraction from crude oil is heating to turn the hydrocarbons into a gas. This is passed over a hot catalyst and thermal decomposition takes place. Large molecules split into smaller, more useful ones.
The generic formula is:
Advantages of Hydrogen
*Advantages of using hydrogen as a fuel:
- It releases lots of energy when burnt
- No harmful gases are produced, only water vapour which is harmless to the environment
Advantages of Ethanol
*Advantages of using ethanol as a fuel:
- It does not affect the performance of the car
- It can save money
- It is carbon neutral
Carbon can make four bonds and hydrogen can make one bond, so that their outer shells are full.
Disadvantages of biofuels
*Disadvantages of using biofuels:
- Much more crops need to be grown
- Crops are likely to rise in price
- Setting up the industry is expensive
- Nitrogen oxides are more concentrated when biofuel is burnt
- Cost of food will increase
- Deforestation occurs
- Lots of water is needed
Biofuel comes from products of organisms e.g. methane from manure or sewage. Vegetable oil is also used, and some biodiesel is made from waste cooking and rapeseed oil.
Monomers are sinle molecules of plastic, which contain double bonds. When joined together, they make polymers.
For example: A pen
They can be recycled, because they become soft and melt when heated. This is because the intermolecular forces are weak and break under heat. The forces reform after heating and the plastic becomes hard again.
Benefits of emulsifiers
- Food is smooth/thick and lasts longer
- Foods sell better and make more money
- Growth of microbes in food is reduced
- Foods look nice
Drawbacks and risks of emulsifiers
- Some are banned in Australia
- Some are linked to asthma
- Some are made from animal products - certain people cannot eat them
- The list of banned emulsifiers is not easily accessible
- You only know if emulsifiers are in foods if you read the small print ingredients
- Some are linked to cancer
- Some are linked to skin irritation
Structure of vegetable oils
They are made of one glycerol molecule for every three fatty acid molecules. Glycerol contains three carbon atoms and fatty acids have a long carbon chain.
Economic impact of polymers
- Fewer trees are cut down
- They are cheap to make
- Jobs are provided in companies manufacturing polymers
- Sorting different polymers can be expensive
The generic formula is:
Fractional Distillation of crude oil
Crude oil is heated in a fractioning column.
Fractions which come off from the top have small molecules, low boiling points, are lightly coloured, easy to set alight and runny. E.g. refinary gas.
Fractions which come off from the bottom have large molecules, high boiling points, are darkly coloured, easy to set alight and are viscous (thick). E.g fuel oil.
Bitumen comes off at the very bottom as a solid.
Burning when there is a reduced amount of oxygen. The formula is:
Hydrocarbon + oxygen ---> carbon monoxide + water + carbon (particles)
Carbon particles are what make smoke black
Alkenes have double bonds and are unsaturated, which means not all bonds are used to link to a different atom - sometimes two bond link to the same atom.
Environmental impact of polymers
- They can be made into new things which saves resources
- Less trees are cut down
- They are made from oil which is non renewable
- Most don't biodegrade so are hard to dispose of
- Landfills where most end up are ugly
- They give off toxic fumes when burnt
Distillation of vegetable oils
- Plants are placed into boiling water
- The oil evaporates from the plants
- The oil is collected by condensing it
- Water and other impurities are removed from the oil