What is fractional distillation?
Fractional distillation is where crude oil is separated into fractions.
What do the properties of each fraction depend on?
The fractions's properties depend on the size of their hydrocarbon molecules.
Characteristics of shorter chained molecules
•Low boiling point •Burn well, good flammability •Cleaner flames •Less viscous •More volatile
Characteristics of longer chained molecules
•High boiling point •Less volatile •Very viscous •Burns with a smoky flame, less flammable
Describe the stages of fractional distillation:
Crude oil is fed near the bottom of the tall tower The oil is vaporised before it goes into the tower The gases condense when they reach the temperature of their boiling points The shorter chained molecules with the low boiling points are near the top and the long chained molecules are at the bottom
What is the purpose of fractional distillation?
Fractional distillation separates crude oil into hydrocarbons with similar boiling points, called fractions. As a result, the longer chained molecules are used in making roads and flat roofs whereas the smaller chained molecules are used to make petrol etc.
What happens when a hydrocarbon burns?
Carbon dioxide and water is released.
What is oxidisation?
Adding oxygen in a reaction in which oxides are formed.
What happens when there isn't enough oxygen inside an engine when the fuels are burned?
We get incomplete combustion. Instead of carbon dioxide, we get carbon monoxide which can cause breathing difficulties as the red blood cells carry this gas around your blood instead of oxygen.
What does the high temperature in an engine do?
The high temperature allows nitrogen and oxygen to react together to form nitrogen oxides. These are poisonous and and can cause acid rain alongside sulphur dioxide.
What are particulates?
Particulates are tiny solid particles containing carbon and burnt hydrocarbons, these particulates can cause damage to cells in the lungs and potentially cancer.
What do particulates cause?
Particulates can reflect sunlight back into space causing global dimming.
How can we reduce the effects of burning fuels?
•Catalytic converters- a catalytic converter reduces the carbon monoxides and nitrogen oxides produced by a car engine. They are expensive but very effective. The metal catalysts are arranged so that they have a large surface area, this causes the carbon monoxides and nitrogen oxides in the exhaust engine to react together. •This forms carbon dioxide and nitrogen. So although toxic gases are prevented- carbon dioxide is still released. •Filters- filters remove the particulates from modern Diesel engines. The filters need to burn off the solid particles or they will get blocked. •In power stations- sulphur dioxide is removed by reacting it with calcium oxide or calcium hydroxide. This is called flue gas desulphurisation.
What are biofuels?
Biofuels are a renewable source of energy that could be used to replace some fossil fuels.
Advantages of biodiesel:
•Biodiesel is less harmful to plants and animals. If it's spilled, it breaks down quicker than normal diesel. •It burns much more cleanly reducing the particulates emitted and it makes very little sulphur dioxide. •Crude oil is likely to increase in price as it is finite, biodiesel will therefore become cheaper to use. •Biodiesel is carbon neutral, this means the carbon dioxide emitted from burning the biodiesel is balanced by the plants used to grow the biodiesel. •When biodiesel is made, other useful products are made too. Solid waste material is produced which can be used to feed cattle as high energy food. Glycerine is also produced which can be used to make soap.
Disadvantages of biodiesel:
•The use of large areas of farmland to produce fuels instead of food could cause food shortages. •People are also worried about the destruction of habitats of endangered species. •Biodiesel freezes at low temperatures and at high temperatures, it can turn sticky.
What is biodiesel?
Biodiesel is made from oils extracted from plants and could be a source of fuel.
What is biogas?
Biogas is generated from animal waste and is potentially a fuel.
Ethanol as a biofuel
Ethanol can be grown from the fermentation of sugar canes.
Hydrogen as a fuel
Hydrogen could potentially become a fuel but there are some issues. Advantages: Hydrogen burns with a clean flame, the only by-product is water. No pollutants such as CO2 are made. Water is readily available and it is a natural source if hydrogen. Hydrogen is Eco friendly. It conserves fossil fuel reserves. Disadvantages: Hydrogen is highly flammable. It takes up a much larger volume than liquid fuels so storage is an issue. Electricity must be used to obtain hydrogen by electrolysis.
Why will biofuels become more important?
They will become more important as our supplies of crude oil will run out.
What is crude oil?
Crude oil is a mixture of many different compounds.
What are alkanes?
Alkanes are saturated hydrocarbons, they contain as many hydrogen atoms as possible in their molecules.
What is the general formula of alkanes?
How to remember the first four alkanes
Monkeys Eat Peanut Butter Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10
What is the general formula for alkenes?
CnH(2n). Alkenes are unsaturated hydrocarbons.
Fractional Distillation Column