4.2 Hydrocarbons & Alkanes
Crude oil is mainly a mixture of hydrocarbons. Hydrocarbons are made up of only hydrogen and carbon atoms. Alkanes are hydrocarbons meaning all of the carbon atoms in a chain are surrounded by hydrogen atoms. Alkanes are different lengths because of the number of carbon atoms that are in them. They follow the formula CnH2n+2. Each carbon atom forms four covalent bonds and each hydrogen atom forms one covalent bond. A covalent bond is whereby two atoms each share an electron with each other. When each atom is forming bonds with as many other atoms as possible we say that they are saturated.
For the exam you need to know the first four alkanes. These are:
For the exam you need to know the first four alkanes. These are:
- Methane: CH4
- Ethane: C2H6
- Propane: C3H8
- Butane: C4H10
Properties of Hydrocarbons
Different hydrocarbons have different properties, such as different boiling points and the flammable nature of each hydrocarbon varies:
The properties of hydrocarbons determine how the hydrocarbons are used as fuel.
Different hydrocarbons have different properties, such as different boiling points and the flammable nature of each hydrocarbon varies:
- Smaller hydrocarbons have a lower boiling point and are gases at room temperature
- Hydrocarbons that have between 5 and 10 carbon atoms are usually liquids at room temperature.
- Hydrocarbons with many more carbon atoms are solids at room temperature and have a high boiling point.
- The shorter the hydrocarbon is, the more flammable it is and the longer the hydrocarbon, the less flammable it is.
- The longer the hydrocarbon, the more vicious it is (i.e. it is gloopier). This is because longer hydrocarbons have a higher boiling point.
The properties of hydrocarbons determine how the hydrocarbons are used as fuel.
Hydrocarbon Uses
However, crude oil is a non-renewable resource meaning that it will run out one day. Scientists are constantly looking for new oil reserves and are advancing technologies so that oil can be taken from parts of the world that were previously not able to be extracted from. For example, oil can be extracted from tar sands. The United States have a lot of oil production that comes from tar sands. Even so, one day all of the fossil fuels will be used up and we will have to generate energy and produce plastics and chemicals in different ways. Some scientists state that we should start changing our behaviour with respect to energy as to conserve the oil that we have now and to slow down the rate at which we are using the oil. For uses whereby there is an alternative fuel use, we should be using the alternative energy rather than fossil fuels. The prime example would be for transportation. There are many reliable and affordable electric cars on the market and governments and authorities should be encouraging consumers to be purchasing electric cars rather than the tradition petrol/ diesel cars. Along with electric cars, we would have to generate electricity in a greener way, such as using renewable energy resources (such as solar, wind, tidal etc.).
However, crude oil is a non-renewable resource meaning that it will run out one day. Scientists are constantly looking for new oil reserves and are advancing technologies so that oil can be taken from parts of the world that were previously not able to be extracted from. For example, oil can be extracted from tar sands. The United States have a lot of oil production that comes from tar sands. Even so, one day all of the fossil fuels will be used up and we will have to generate energy and produce plastics and chemicals in different ways. Some scientists state that we should start changing our behaviour with respect to energy as to conserve the oil that we have now and to slow down the rate at which we are using the oil. For uses whereby there is an alternative fuel use, we should be using the alternative energy rather than fossil fuels. The prime example would be for transportation. There are many reliable and affordable electric cars on the market and governments and authorities should be encouraging consumers to be purchasing electric cars rather than the tradition petrol/ diesel cars. Along with electric cars, we would have to generate electricity in a greener way, such as using renewable energy resources (such as solar, wind, tidal etc.).