Materials obtained or made from living things are sometimes called natural materials, whereas synthetic materials are made from chemicals. Today, synthetic materials offer us more durability at a lower cost than the natural materials we used to use.
Synthetic and Natural Materials
The materials we use are chemicals or mixtures of chemicals. For example, sugar is a chemical, but chocolate is a mixture of chemicals, one of which is sugar. Materials can be obtained or made from living things. Examples include cotton, paper, silk and wool. These are sometimes called natural materials. Materials can also be made from chemicals. Examples of these include plastics such as polythene used in plastic shopping bags. These are called synthetic materials.
Refining Crude Oil
Crude oil is a raw material obtained from the Earth’s crust. It is a mixture of many different chemicals, most of which are hydrocarbons. These are chain molecules of varying length that are made from hydrogen and carbon atoms only. Crude oil is not very useful until it has been processed at an oil refinery. The process of refining involves separating the hydrocarbons into fractions or batches using a technique called fractional distillation. Each fraction separates as they have different boiling points. The crude oil is heated in a furnace to around 400°C. This allows all of the hydrocarbons in the crude oil to move into the bottom of the fractionating tower. The tower is hottest at the bottom and coolest at the top. The smallest molecules contained in the crude oil have lower boiling points and so move to the top of the tower. This is because the forces between these molecules are weak, so little energy is required to vaporise them. Larger molecules will…