1. © KCL. WCED. PENTECH. 2002 Materials and lives Briefing sheet Your group will be given a sheet on one topic in the series on Materials and Lives. Each sheet covers a different topic about how different materials enable people to do different things. There are sheets on - Cleaning dirty clothes, - Designing drugs, - Going places, - Communicating, - Cutting - Cooking Food. Your task * READ the information sheet carefully. * DRAW UP a time line for how long ago things happened. This means you draw a line and mark off the years and centuries along the line. Add markers for when things happened for your topic. * DECIDE on which materials are involved at any one period of time. WRITE down the materials involved. * DESCRIBE how the different materials would have changed different people’s live and those of the world population. Your report to the class * DISCUSS your presentation with your group members. * ARRANGE for each member to make some part of the presentation. * PREPARE any diagrams, posters, charts or pictures you will need. * MAKE your group presentation.

2. © KCL. WCED. PENTECH. 2002 Materials and lives Cleaning dirty clothes Dry cleaning is a way of cleaning clothes without using any water. Instead, a solvent is used that dissolves oils and fats. This loosens most of the dirt on the clothes. Carbon tetrachloride (CCl 4 ) was a popular dry cleaning agent until it was discovered that its fumes caused cancer. Now other alternatives are used. 5,000 years ago people would wash their clothes by flushing them with water while beating the cloth to loosen the unwanted particles of dirt. It was hard work. 2,000 years ago the Romans made soap and used it to wash clothes. Soap is a chemical made from adding sodium hydroxide (NaOH) to oil or a melted fat. It was a messy process and the soap was expensive. Only the rich could afford to wash their clothes this way. Sodium carbonate (Na 2 CO 3.10H 2 O) can be used to soften water. In the 19th century, in Belgium, Solvay took out patents on a way of making sodium carbonate cheaply.Washing soda, as the chemical is commonly called, made keeping clothes clean much cheaper. In 1913 the first artificial soap was made. These detergents are powerful degreasing agents. They are cheap to make and washing clothes becomes much easier. In 1967 Proctor and Gamble introduce The first washing powder that uses biological enzymes to help digest stains.

3. © KCL. WCED. PENTECH. 2002 Materials and lives Designing drugs It is the 1740s and sailors on long voyages are prone to easy bruising, weak joints and rotting teeth falling out. The doctors call these symptoms scurvy. James Lind finds that some substance in the juice of limes and lemons cures scurvy. Earlier, he had tried cider, vinegar, sea water, garlic pills and even sulphuric acid. In traditional communities there are usually one or two people who know how to use the substances in plants to cure some common medical complaints. The leaves and bark of willow trees, the juice from the head of opium poppies, coca leaves have been, and still are, used to relieve pain. It is 1785. Routinely some people are diagnosed by their doctors as having dropsy. They are weak, become bloated, are short of breath and look pale. William Withering hears of an old herbalist who uses foxglove seeds to cure dropsy. He carries out systematic experiments on 160 patients to test the effectiveness of the seeds as a drug. He publishes the results of his clinical trials. It is 1966 and Dorothy Crowfoot Hodgkin is awarded a Nobel Prize for her work. She has been investigating the arrangement of atoms in the molecules of penicillin, Vitamin B12 and insulin. Modern chemists can work out the actual positions of atoms in different molecules. With a knowledge of which parts of a molecule are most effective in producing a cure, chemists can design drugs by placing the atoms in the right order inside the molecules of the drug. Sometimes they can do this with genetic engineering

4. © KCL. WCED. PENTECH. 2002 Materials and lives Going places Even with a horse, you can not travel that quickly. The cells in muscles just do not burnthe glucose (C 6 H 12 O 6 ) fuel fast enough to release sufficient energy. Aeroplanes also have to carry their fuel with them. So some of the fuel is used to lift and move the fuel itself. We don’t have wood burning planes. Burning wood, or coal, is a chemical reaction. The reaction could not release enough energy to lift the plane and the wood from the ground. 1939. Flight of first jet powered plane To travel into space needs a lot of energy. The fuel used is liquid hydrogen (H 2 ). Liquid hydrogen is not very dense and each kilogram takes up about ten times more space than one kg. of aeroplane fuel. Rockets are BIG because they have to carry lots of fuel - hydrogen and oxygen. 1961. Yuri Gagarin is the first person in space. Cars do not have to lift themselves off the ground. They can use a fuel that contains less energy per kilogram than the fuel used in aeroplanes. Like aeroplanes the fuel for cars comes from oil. The molecules of oil contain carbon (C) and hydrogen (H) atoms. 1890s. Cars with petrol engines are made. The first form of combustion engine was the steam engine. In the chemical reaction of burning coal, less energy is released per kilogram than when burning fuel oil used in cars and planes. 1830s. Steam engines Start pulling trains of carts

5. © KCL. WCED. PENTECH. 2002 Materials and lives Communicating 170 years ago, copper (Cu) wires were used to send electric currents as messages. Initially these messages warned railways staff of approaching steam trains. From 1875 onwards the telephone enabled people to speak to each other across long distances. More than 20,000 years ago people discovered how to use paints for wall paintings. They used these paintings to store and communicate ideas on the world about them. Such rock paintings communicated messages long after the original authors were dead. By 5,000 years ago people had become skilled enough to use hard rocks, like granite, to chip at softer rock, like limestone and marble, to create messages in pictures and early forms of writing - like Egyptian hieroglyphs. These messages, being in the rock, were not transportable. The invention of paper made writing more transportable. 1,700 years ago the great library in Alexandria stored 500,000 texts collected from various places in the eastern Mediterranean. Unfortunately it burnt down. With the manufacture of better quality glass in the seventeenth century, telescopes could be used to read the messages signalled with different coloured flags. This was called semaphore and proved particularly useful at sea. 60 years ago, the use of silicon (Si) enabled engineers to make transisters. These were followed by micro-chips. The electronics of the computer, e-mail and the inter-net also depends on micro-chips. Modern micro-chip electronics has allowed us to invent and use mobile-phones. They use of radio waves to send and receive signals and do not need connecting wires.

6. © KCL. WCED. PENTECH. 2002 Materials and lives Cutting Natural flint can be found lying on the ground in some places. The flint contains the chemical elements silicon (Si) and oxygen (O). In the flint there are large crystal like structures. The crystals can be struck so they break and form sharp edges. The pieces of flint can be used as knives. 30,000 years ago. Flint knives. Copper and tin are found in certain rocks in the form of their ores. Both copper (Cu) and tin (Sn) can be extracted by the chemical reaction produced on heating. With tin the ore must be heated with charcoal. If tin and copper are mixed they form a new material: bronze. The bronze alloy is strong and can be used to make heavy cutting tools like axes. 5,000 years ago. Bronze axe. 3,500 years ago. Iron swords. Iron (Fe) melts at a temperature 500 o C higher than copper or tin. To extract iron from its ores needs a temperature of at least 1,500 o C. Iron is stronger than bronze and can be worked to give a sharper edge. The stronger metal supports a thinner blade. Modern steel kitchen knife. 1,200 years ago people learnt to control the melting of iron and the addition of a carbon impurity. The combination of iron and carbon produces a new material: steel. Steel is very strong and can be worked to give an even finer edge, and therefore sharper blade, then iron.

7. © KCL. WCED. PENTECH. 2002 Materials and lives Cooking food 400,000 years ago early humans were hunter gatherers. That is they got their food by gathering berries,fruit, wild roots and hunting smaller animals and some fish. Early humans would have eaten the meat from the animals raw - uncooked. From remains in caves, we know that people were using fire at least 100,000 years ago. With fire they could have cooked the meat from the animals they had hunted and butchered. There was a braai when an animal was caught. About 7,000 years ago people were using stone ovens to bake bread from wheat and rye flour. The same ovens Were used to make pots from clay. Clay is a mixture of oxides -(AL 2 O 3.2SiO 2.2H 2 O). With a clay pot it is possible to boil water and make porridges from cereals like oats, barley and wheat, as well as making stews from meat and vegetables. Changes to cooking food over the next 7,000 years depended mainly on the type Of implement used to eat the food. In the east people developed the use of chop-sticks made from wood. In the west, people developed the use of forks from silver (Ag) and iron (Fe). Nearly everyone had spoons. These were made from wood, clay or metal. In the nineteenth century, iron became cheap. People bought and used iron stoves heated by burning coal or wood. In the early twentieth century glass enamels were developed to coat steel and these were used to make gas fired cookers. With the production of the micro-wave oven in 1965 food could be cooked by radio waves. Plastic containers have to be used to let the radio waves get to the food.The food cooks in minutes.