agriculture, provide food, timber, clothing and fuels. Finite resources from the Earth, oceans and atmosphere are processed to provide energy and materials. Chemistry plays an important role in improving agricultural and industrial processes to provide new products. It’s also important in sustainable development, which is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs. resources appropriate information. Extract and interpret information about resources from charts, graphs and tables. Use orders of magnitude to evaluate the significance of data. WS 3.2 MS 2c, 2h, 4a 4.10.1.2 Water of appropriate quality is essential for life. For humans, drinking water should have sufficiently low levels of dissolved salts and microbes. Water that is safe to drink is called Distinguish between potable water and pure water. Describe the differences in treatment 2 Define the terms: potable water pure water. Explain the differences between the two terms. Required practical 8: Analysis and purification of water samples from different sources, including pH, dissolved solids and distillation. Video clip YouTube: Resources for schools -
potable water. Potable water is not pure water in the chemical sense because it contains dissolved substances. The methods used to produce potable water depend on available supplies of water and local conditions. In the UK, rain provides water with low levels of dissolved substances (fresh water) that collects in the ground, in lakes and rivers, and most potable water is produced by: choosing an appropriate source of fresh water passing the water through filter beds sterilising. Sterilising agents used for potable water include chlorine, ozone or light. If supplies of water are limited, desalination of of ground water and salty water. Give reasons for the steps used to produce potable water. WS 2.3, 2.4, 2.5, 2.6, 2.7 Extended writing: describe the process of desalination. Extended writing: describe the process of distillation Extended writing: explain why distillation separates substances. Grade 9: explain what happens to substances during the process of distillation in terms of intermolecular forces of attraction. AT skills covered by this practical activity: 2, 3 and 4. Video clip YouTube:
salty water or sea water may be required. Desalination can be done by distillation or by processes that use membranes such as reverse osmosis. These processes require large amounts of energy. 4.10.1.3 Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment. Sewage and agricultural waste water require removal of organic matter and harmful microbes. Industrial waste water may require removal of organic matter and harmful chemicals. Sewage treatment includes: screening and grit removal sedimentation to produce sewage sludge and effluent Comment on the relative ease of obtaining potable water from waste, ground and salt water. 1 Research how water is treated. Extended writing: detail the methods involved. Several water companies provide resources for schools regarding sewage treatment, for example: Video clip YouTube:
anaerobic digestion of sewage sludge aerobic biological treatment of effluent. 4.10.1.4 (HT only) The Earth’s resources of metal ores are limited. Copper ores are becoming scarce and new ways of extracting copper from ores include phytomining and bioleaching. These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock. Phytomining uses plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds. Bioleaching uses bacteria to produce leachate solutions that contain metal compounds. The metal compounds can be processed to obtain the metal. For example, Evaluate alternative biological methods of extraction, given appropriate information. 1 Extended writing: describe the processes of phytomining bioleaching. Evaluate the impacts and benefits of biological methods of extracting Research information for the processes of: phytomining bioleaching. Include percentage of metal extracted, concentration of global warming gases released, amount of electricity used etc. Use this data in an evaluation. It may be possible to model phytomining in the laboratory by watering geraniums with dilute copper sulphate for a period of time. The leaves can be burnt and copper can be extracted from the ash by rinsing in dilute hydrochloric acid and electrolysing the solution. Video clip YouTube:
Reference to past questions that indicate success 4.10.3.1 Corrosion is the destruction of materials by chemical reactions with substances in the environment. Rusting is an example of corrosion. Both air and water are necessary for iron to rust. Corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating. Aluminium has an oxide coating that protects the metal from further corrosion. Some coatings are reactive and contain a more reactive metal to provide sacrificial protection, eg zinc is used to galvanise iron.. Describe experiments and interpret results to show that both air and are necessary for rusting. Explain sacrificial protection in terms of relative reactivity. WS 2.2, 2.7, 3.5 2 Define the following terms using suitable examples: corrosion rusting sacrificial protection. Describe how to prevent corrosion using the examples: oxide coating on aluminium zinc on iron magnesium on steel. Use suitable examples to explain why corrosion can be prevented using barriers and the role of sacrificial barriers if appropriate to the example used. Investigate the conditions for rusting of iron nails in test tubes. Video clips: YouTube: 4.10.3.2 Most metals in everyday use are alloys. Bronze is an alloy of copper and tin. Brass is an alloy of copper and zinc. Gold used as jewellery is usually an alloy with silver, copper and zinc. The proportion of gold in the alloy is measured in carats, with Recall a use of each of the alloys specified Interpret and evaluate the composition and uses of alloys other than those specified, given appropriate information. MS 1a, 1c 1 Define the terms: alloy high carbon steel low carbon steel. Using diagrams, describe the difference between metals and their alloys. Describe the composition of common alloys and their uses. Research the first alloy to include the history of it and its uses. an alloy using different size marbles. Use this model to discuss the properties of alloys. Research the composition and uses of alloys. Use this Video clips:
pure gold being 24 carat. 18 carat gold is 75% gold. Steels are alloys of iron that contain specific amounts of carbon and metals. High carbon steel is strong but brittle. Low carbon steel is softer and more easily shaped. Steels containing chromium and nickel (stainless steels) are hard and resistant to corrosion. Aluminium alloys are low density. State properties of examples of alloys. Explain, in relation to the structure, why these alloys have these properties. information to evaluate the use of the alloys. The Royal Society of Chemistry has many resources to support teachers in the classroom – including practical guides and instructions: 4.10.3.3 Most of the glass we use is soda-lime glass, made by heating a mixture of sand, sodium carbonate and limestone. Borosilicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass. Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace. The properties of polymers depend on what monomers they are made from and the conditions under which they are made. For example, low density (LD) and high density Explain how low density and high density poly(ethene) are both produced from ethene. Explain the difference between thermosoftening and thermosetting polymers in of their structures. Compare quantitatively the physical properties of glass and clay ceramics, polymers, composites and metals. Explain how the properties of materials are related to their uses 2 Describe how the following are produced and give uses for each: soda-lime glass borosilicate glass clay ceramics low-density poly(ethene) high density poly(ethene) composites. Using diagrams, describe the structure of the following polymers: thermosoftening thermosetting. Use these diagrams and descriptions to explain why the following happens when heated: Research the physical properties of: soda-lime glass borosilicate glass clay ceramics low-density poly(ethene) high density poly(ethene) composites Use these properties to explain how the materials are related to their use. Compare the properties of thermosetting and thermosoftening polymers. More information about glass: Video clips: See also the series ‘How It’s Made’ eg: Composite materials: clips YouTube: (long)
(HD) poly(ethene) are produced from ethene. Thermosoftening polymers melt when they are heated. Thermosetting polymers do not melt when they are heated. Most composites are made of two materials, a matrix or binder surrounding and binding together fibres or fragments of the other material, which is called the reinforcement. and select appropriate materials. WS 1.4, 3.5, 3.8 thermosoftening polymers melt thermosetting polymers do not melt. 4.10.4 The Haber process and the use of NPK fertilisers Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing Opportunities to develop Scientific Communication skills Opportunities to develop and apply practical and enquiry skills Self/peer assessment opportunities and resources Reference to past questions that indicate success 4.10.4.1 The Haber process is used to manufacture ammonia, which can be used to produce nitrogen-based fertilisers. The raw materials for the Haber process are nitrogen and hydrogen. Recall a source for the nitrogen and a source for the hydrogen used in the Haber process. (HT only) Interpret graphs of reaction conditions versus rate. 2 where the raw materials in the Haber process come from. Describe the process for manufacturing ammonia. Research the availability and cost of the raw materials and energy supplies in the process. Explain how these relate to the conditions used for the Haber process in industry. Video clips YouTube: