1. Nitrogen reacting with oxygen to form Nitrogen monoxide Hydrogen reacting with oxygen to form water Combustion Air Pollutants Atoms Earth’s Atmosphere Car engines use catalytic converters to reduce the amount of pollution released. How it works: Molecules of polluting gases are pumped from the engine past the catalyst. The catalyst splits up the molecules into their atoms. The atoms then recombine into molecules of relatively harmless substances such as carbon dioxide, nitrogen, and water, which blow out safely through the exhaust. What influences Air Quality? 1. Emissions Vehicles release pollutants into the air. 2. Weather Winds mix up and transport pollutants. Combustion (burning) reaction Some chemicals can react rapidly with oxygen to release energy and possible light. Carbon reacting with oxygen to form carbon monoxide Incomplete combustion If there isn’t enough oxygen to the burn the fuel completely, incomplete combustion takes place. Carbon monoxide is formed. It also releases small particles of carbon into the air. Conservation of atoms Reactants → Products The products have different properties from the reactants. As a chemical reaction takes place, atoms in the reactants are rearranged to make the products. No atoms are added or taken away. The Earth’s atmosphere provides a protective blanket that supports life. Human activities have altered the balance of these chemicals as it can be damaged easily. The concentration of C0 2 doubled since the burning of fossil fuels. A primary pollutant is an air pollutant emitted directly from a source. A secondary pollutant is not directly emitted, but forms when other pollutants (primary) react in the atmosphere. Example: N0 joins with oxygen atoms in the air to form N02. C1

2. Polymer with no cross-links Polymers Molecular Structure Life Cycle Assessment Material Properties What are Polymers? A polymer is a long-chained molecule that is composed of individual units of ethene, called monomers. Materials can be obtained or made from living things and chemicals. These are known as natural and synthetic materials. A Life Cycle Assessment, or LCA, is a study of the stages in the life of a manufactured product. It can be used to assess the environmental impact of the manufacture and use of different materials and products. The shape and size of the long- chain molecules in a fibre make the material what it is and gives it it’s special properties. By polymerising other small molecules, a wide variety of different polymers can be made. These synthetic materials have many uses. Ethene makes polythene Modifying polymers Different polymers have different properties, depending on the small molecules they were made from; but the properties of a polymer can also be changed. Many polymers, such as polythene, contain long molecules that lie side by side. These can uncoil and slide past each other, making the material flexible. Long polymer chains have stronger forces of attraction than shorter ones. By making the chains of a polymer longer, a stronger and less flexible material is produced. Polymer chains CRADLE USE GRAVE The raw materials for making the product The energy used to manufacture it The energy needed to use it The energy needed to maintain it The chemicals needed to maintain it The raw materials for making the product The energy used to manufacture it Getting the right material The products that we use are made of different materials. Choosing the right material for each job depends on the properties of that material. Manufacturers and designers have to choose the right materials to make their products. They decide which materials to use based on their properties and cost. Getting the right material The products that we use are made of different materials. Choosing the right material for each job depends on the properties of that material. Manufacturers and designers have to choose the right materials to make their products. They decide which materials to use based on their properties and cost. Solid materials can differ in the following ways: Melting point Strength in tension (when pulled) Strength in compression (when pushed) Stiffness Hardness Density Nylon is used to make tights due to its flexibility. C2

3. Polymer with cross-links Vulcanisation PVC and uPVC LDPEHDPE Low-Density Polythene (LDPE) The side branches stop the polymer molecules from lining up regularly. Its structure is not crystalline. This means that: The material has a lower density than HDPE. The forces of attraction between polymer molecules are weakened. The material is less strong and has a lower melting point than HDPE. No side branches Has side branches Various amounts of crystallinity By carefully controlling the amount of branching, it is possible to make polymers with various amounts of crystallinity. This means it is possible to make a polymer with the exact properties that are required for a particular purpose. High-Density Polythene (HDPE) The polymer molecules line up regularly to give a crystalline structure. This means that: The material has a higher density than LDPE. The forces of attraction between polymer molecules are strong. The material is stronger and has a higher melting point than LDPE. PVC Molecules Plasticizers Plasticizer molecules behave like ‘molecular lubricants.’ They push the polymer molecules slightly further apart. This weakens the intermolecular forces between them and allows the polymers chains to slide over each other more easily, making the material softer and more flexible. Unplasticized PVC, usually called uPVC, is hard. Plasticised PVC is soft. Side Branches When polythene molecules made from ethene are exposed to pressure, side branches are given off. The polymers will still grow but from multiple branches and will not line up neatly. LDPE in an example of this. Sulphur What is Vulcanisation? Natural rubber is sticky, deforms easily when warm, and is brittle when cold. In this state it cannot be used to make products with a good level of elasticity. Vulcanisation is the process in which rubber is heated at high temperatures with sulphur. The sulphur forms chemical bonds, or cross-links, which link together the chains of individual polymers. These cross-links lock the material in a regular shape and make the material tougher and less flexible, increasing its worth and uses. C3

4. Preserving and Processing Food Natural Polymers FarmingDiabetes Food Additives Colourings: Replace or add [natural] colours. Flavourings: Gives the food a certain taste Sweeteners: Increase sweetness and replaces sugar in products using artificial sweeteners such as aspartame. Emulsifiers: Help to mix together substances which do not easily mix, such as oil and water. Stabilisers: Stops these substances separating again after they have been mixed. Preservatives: Prevents growth of microbes such as bacteria in foods during storage to increase shelf life. Antioxidants: Prevents reaction of chemicals in food with oxygen in the air. E Numbers A food additive that has passed safety tests to allow its legal use in the EU is given an E number. E100 series: Colours E200 series: Preservatives E300 series: Antioxidants E400+ series: Emulsifiers, stabilisers and other additives Diabetes is a condition where the amount of glucose in your blood is too high because the body cannot use it properly. Insulin is the hormone produced by the pancreas that allows glucose to enter the body’s cells, where it is used as fuel for energy. Glucose comes from digesting carbohydrate and is also produced by the liver. Diabetes is a condition where the amount of glucose in your blood is too high because the body cannot use it properly. Insulin is the hormone produced by the pancreas that allows glucose to enter the body’s cells, where it is used as fuel for energy. Glucose comes from digesting carbohydrate and is also produced by the liver. High Blood Glucose Level Pancreas produces insulin which enters the blood. Insulin allows the glucose to be absorbed by body cells, reducing blood glucose. Low Blood Glucose Level Pancreas stops producing insulin. This results in less glucose being absorbed by the body cells and more to accumulate in your blood. Carbohydrates and proteins Many of the chemicals in living things are natural polymers. Animals and plants need natural polymers like proteins and carbohydrates. Food contains natural polymers which are broken down during digestion into soluble compounds. These are absorbed into the blood and transported around the body. The breakdown products are then used by the body to make new polymers, during a process called Synthesis. Carbohydrates and proteins Many of the chemicals in living things are natural polymers. Animals and plants need natural polymers like proteins and carbohydrates. Food contains natural polymers which are broken down during digestion into soluble compounds. These are absorbed into the blood and transported around the body. The breakdown products are then used by the body to make new polymers, during a process called Synthesis. Carbohydrate Sugar Molecule Protein Amino Acid Molecule Natural Cycle of Nutrients As plants grow they remove NPK from the soil and it becomes less fertile. Farmers need to be able to replace elements that are removed by plants and stop weeds, pests and disease. These elements are returned to the soil when living organisms die and decay, or when animals eat other living things. These processes means that there is a continuous cycling of elements. Natural Cycle of Nutrients As plants grow they remove NPK from the soil and it becomes less fertile. Farmers need to be able to replace elements that are removed by plants and stop weeds, pests and disease. These elements are returned to the soil when living organisms die and decay, or when animals eat other living things. These processes means that there is a continuous cycling of elements. Plants make their own food through photosynthesis. They require hydrogen, carbon, oxygen, NPK and water for growth. Intensive farming involves using loads of artificial fertilisers, herbicides and pesticides and means growing just one crop year after year. Organic farming aims to produce crops without using artificial fertilisers. C3