Topic 5 – Synthesis
Crude oil fractions burn cleanly, so they make good fuels. Most modern transport is fuelled by a crude oil fraction. Gas and oil are burnt in central heating in homes, and in power stations to generate electricity. Often there are alternatives to using crude oil fractions as fuels for example electricity can be generated by nuclear or wind power, there are ethanol powered cars, and solar energy can be used to heat water. But things tend to be set up for using crude oil fractions. For example, cars are designed for petrol or diesel and they’re readily available. There are filling stations all over the country, with specially designed storage facilities and pumps. So crude oil fractions are often the easiest and cheapest things to use. Crude oil fractions are also often more reliable, for example, solar and wind power need the right weather conditions. Nuclear energy is reliable, but there are lots of concerns about its safety. As well as fuels, crude oil provides the raw materials for making various chemicals, including plastics, paints, solvents, detergents and lots of medicines. Crude oil is so useful because it is mainly carbon. Each carbon atom forms four covalent bonds, which can join atoms together in lots of different ways. Carbons can be arranged in chains or rings, they can be linked together with single, double or triple covalent bonds and can have many other elements bonded onto them. Unlike most other elements, carbon can form huge molecules containing hundreds of atoms joined together, for example the human insulin as well as many different plastics. Most scientists think that oil will run out but no one knows exactly when. New oil reserves are discovered from time to time but no one knows how much oil will be discovered in the future though. Also, technology is constantly, improving, so now it’s possible to extract oil that was once too difficult or expensive to extract. It is likely that technology will improve further. In the worst case scenario, oil may be gone in about 25 years Some people think we should immediately stop using oil for things like transport, for which there are alternatives, and keep it for things that it is absolutely essential for, like some chemicals and medicines. It will take some time to develop alternative fuels to satisfy all our energy needs and to adapt things so the fuels can be used on a wide scale, for example, design new car engines or special storage tanks. So however long oil does last for it is a good idea to start conserving it and finding alternatives now.
Alkanes and Alkenes
Alkanes are made of chains of carbon atoms with single covalent bonds between them. They are called saturated hydrocarbons because they have no spare bonds. This is why alkanes don’t decolourise bromine water because they have no spare bonds. Alkanes won’t form polymers, for the same reason again, they…