How many nm are in a metre? [1]

1. Explain what nanoparticles are, and suggest why some act as catalysts. [4] Read the newspaper article. Skincare creams use nanotechnology Nanoparticles are put in face creams and sunscreens. These creams are easy to apply and invisible on the skin. Some scientists are worried about the effects of nanoparticles on the body. At the moment it is impossible for consumers to tell if the creams contain nanoparticles. Here are the sizes of some silver particles. Two of them are nanoparticles. Put rings around the two nanoparticles. [1] 0.1nm 10nm 50nm 500nm 1000nm Suggest why silver nanoparticles have different properties to a lump of silver. [2] How many nm are in a metre? [1] Use your knowledge of nanoparticles to explain why some scientists may be worried about the effects of using these particles in creams. Suggest what actions should be taken to reduce the concerns of experts and consumers. [6] • Nanoparticles are used in a wide variety of products. • Some scientists are worried about this. • Which two statements give reasons for their concern? • Put ticks () in the boxes next to the two correct answers. [2] • Nanoparticles do not occur in nature. • Nanoparticles have a smaller surface area than larger particles. • The effects of nanoparticles have not yet been fully investigated. • Nanoparticles are larger than 1000nm • Nanoparticles may be harmful to health. • Nanoparticles are too small to be seen by the unaided eye.

2. What are synthetic materials , and what advantages do they have over natural materials? [4] Scientists working for a shoe company look at materials that could be used to make walking shoes. Anna and Nick are investigating the properties of vaulting poles. They know flexibility is an important property. They support the pole at both ends as shown in the diagram. They hang a 200N weight from the centre of the pole and measure how far the pole bends. They repeat this measurement five times. Suggest reasons why. The table shows some of the properties of several materials used in shoes. Write in the missing property to complete each sentence. The temperature at which a solid turns to a liquid. _________ The force needed to crush a material. _________ How well a material stands up to wear. _________ The mass of a given volume of material. _________ [1 mark each] Choose which material would be best for the upper and which would be best for the sole of these walking shoes. Explain your choices. [6] Draw lines to match each material to its best property and to its use. [2]

3. Petroleum gas and liquid fuel oil have very different boiling points. Describe the sizes of the molecules in petroleum gas and fuel oil and explain why they boil at different temperatures. [4] During the refining process crude oil is heated. The hydrocarbons are vapourised and then condensed into fractions. Which of these statements explains why this process separates the hydrocarbons into fractions? Put ticks () in the boxes next to the two best statements. [2] Use the information below to describe the link between the size of the molecules in each fraction and the temperature at which the fraction boils. Explain this pattern using ideas about forces, molecular size and the way in which molecules are arranged in liquids and gases. [6] Crude oil is a mixture of hydrocarbons. Name the two elements found in hydrocarbons. elements ________ and _________ [1] Compounds A, B, C, D and E are found in crude oil. The diagram shows a molecule of each of these five compounds. • The energy needed to break molecules away from each other decreases as they get bigger. • The longer the hydrocarbon chains, the larger the forces between them. • All hydrocarbons boil at the same temperature. • Small molecules are held together by larger forces than large molecules. • Large molecules need more energy to vapourise than small molecules. • Small molecules boil at higher temperatures than large • molecules. Which compound is not a hydrocarbon? ____ [1] Which compound has the largest forces between its molecules? ____ [1] Which compound has the lowest boiling point? ____ [1] Crude oil is a mixture of hydrocarbons. It is refined to make chemicals that are used in different ways. One way they are used is as raw materials, for example to make polymers. Write down two other ways that chemicals from refined crude oil are used. [2]

4. Describe plasticisers and how they work. [4] Modifying polymers changes their properties. Students test two different samples of polypropene. Here are their measurements. Draw a straight line from each change in property to the modification and another straight line from each modification to the reason why it works. [3] Ethene is the monomer for making polythene. What is the name of the process for making poly(ethene) from ethene? [1] The diagram shows a polymer before and after modification. The properties of polymers can be changed by modifying their structures. Suggest and explain why the two samples of polypropene have different properties. [6] What has been modified in this polymer? Put a ring around the correct answer. chain length cross linking crystallinity plasticizer [1] Long chain molecules in plastics can be modified to change their properties. What effect do the following modifications have on the melting point of a plastic? Put a tick () in the correct box for each modification. [2]