Without carbon fuels life would be very different. They are used to generate our electricity, power our vehicles, heat our homes and much more besides. But burning fossil fuels comes at an environmental cost - they cause pollution in the air that we breathe in several different ways. This GCSE Chemistry quiz is all about burning carbon fuels (commonly known as fossil fuels) and the pollution that this causes.
The fossil fuels are coal, oil and gas and are so-called because they were formed long ago in the past. All three are extracted from the rocks of the Earth - coal by digging it out and the other two by drilling. They are formed from the remains of plants (coal) and sea creatures (oil and gas) that have died. Under the right conditions, these decay to form the fossil fuels. They take millions of years to form and so they are regarded as non-renewable, but that is the subject of other quizzes.
This quiz is concerned with the burning of the three fossil fuels and some of the problems this causes. Coal is mainly carbon and tar, which is a thick, sticky hydrocarbon. Oil is made from a mixture of liquid hydrocarbons (predominantly members of the alkane family), whilst natural gas is essentially the alkane with the smallest molecule - methane. Since these formed from living organisms, there are traces of the element sulphur (and others too) that have come from their proteins.
When anything burns, it is an oxidation reaction. In other words, the elements of the material being burnt become oxides. So when hydrocarbons burn, the hydrogen becomes water and the carbon becomes carbon dioxide (or carbon monoxide when incomplete cumbustion takes place). Since coal and oil contain a lot of carbon in their compounds, they produce a lot of carbon dioxide and carbon monoxide. Carbon monoxide is toxic, it prevents the blood from carrying oxygen. Carbon dioxide is a greenhouse gas and the vast majority of scientists believe that the increase of carbon dioxide in the air is a significant cause of global warming.
There is another kind of pollution caused by burning fossil fuels. When the sulphur burns, it forms acidic oxides causing acid rain. This problem has been reduced in many developed countries as petroleum companies remove as much of the sulphur as they can from the fuels they sell.
Which of the following is a disadvantage of using biofuels?