One of the topics covered in GCSE Science is the chemistry of crude oil and other fuels. This is the first if six quizzes on that subject and it looks in particular at the hydrocarbons and alkanes which are found in crude oil.
Crude oil formed over a long period of time - millions of years in fact. It formed from the remains of dead sea creatures and plants that rotted down anaerobically (with little or no oxygen) as they became buried with sediments on ancient sea beds. The oil is trapped underground by layers of impermeable rocks and is extracted from the ground by drilling oil wells.
But what is the chemistry of crude oil? Well, it is a mixture of thousands of different chemicals which are mainly hydrocarbons. These are covalently bonded molecules made mainly from the elements hydrogen and carbon, in fact, most are only made from those two elements and are that is why they are called hydrocarbons.