Chemistry - Polymers

Crude oil straight from the ground is not a particularly useful material but, after fractional distillation, it provides us with many different types of fuel. These fuels are all members of one large chemical family, the alkanes. But when some of the fractions of crude oil are 'cracked', a whole new world of chemistry opens up. The reason for this is that cracking produces a new family of chemicals, one which wasn't present in the oil to begin with. This new family of chemicals is the alkenes.

The alkenes are so useful because they are 'unsaturated'. That means that they contain at least one double bond between carbon atoms. This double bond means that they are more reactive than the alkanes and in different ways too. They can be made into aldehydes, alcohols and all manner of other chemicals but probably the best known and most useful in everyday life are the polymers.

Polymers take different forms. Cellulose is a natural polymer that is made by plants. This is not a polymer of an alkene but of glucose molecules, joined together in long chains. Rubber is a polymer too. But the polymers that this quiz is all about are the polymers that can be made from oil and oil products - these are the plastics.

The simplest of the alkenes is ethene. This is two carbon atoms joined together by a double bond. Attached to each of the carbon atoms are two hydrogen atoms so the formula is C₂H₄. Ethene molecules can be joined together to form long chains or polymers making the plastic that you know as polythene. Polythene is a trademark invented by the chemical company ICI. Its scientific name is poly(ethene).

The chemicals from which a polymer is made are called monomers. So, if the starting chemical, the monomer, is styrene, the polymer made from it is polystyrene and so on. So actually, you can often work out the starting chemical from the name of a polymer. The scientifically accepted way of writing the name of a polymer is poly(ethene), but it is also commonly written as polyethene.

Try this quiz to see how well you understand the chemistry of the polymers.