using resources

• Ceramics are non-metal solids with high melting points. Some ceramics are made from clay - a soft material which can be moulded into different shapes, but hardens at high temperatures. This makes it ideal for pottery and bricks.
• Another ceramic is glass, which is generally transparent. It can be moulded when hot and can be brittle when thin. There are two types:

  • soda-lime glass - made from limestone, sand and sodium carbonate
  • borosilicate glass - made from sand and boron trioxide. It has a higher melting point than soda-lime.
• Composites are made by mixing two or more materials together to create a new material with a new set of properties. Fibres or fragments of a material (reinforcement) are surrounded by a matrix acting as a binder.
• Fibreglass consists of fibres of glass embedded in a matrix made of polymer. It has a low density but is very strong. Used for things like skis, surfboards and boats.
• Carbon fibre composites also have a polymer matrix; the reinforcement is made from either long chains of carbon or from carbon nanotubes. These are very strong and light, so can be used in aerospace and sports cars.
• Concrete is made from aggregate embedded in cement. It is very strong, so it can be used as building material.
• Wood is a natural composite of cellulose fibres held together by an organic polymer matrix.
• Low density (LD) poly(ethene) is made from ethene at moderate temperatures and high pressure. It is flexible and is used for bags and bottles.
• High density (HD) poly(ethene) is made from ethene at lower temperatures and pressures with a catalyst. It is more rigid and is used for drainpipes.
• Thermosetting polymers contain monomers with cross-link between chains in a solid structure. They don't soften when heated and are strong, hard and rigid.
• Thermosetting polymers contain individual chains entwined together with weak forces between. They melt and soften, and can be remoulded.
• Ceramics include glass and clay ceramics such as porcelain and bricks. They are insulators of heat and electricity, brittle and stiff.
• Polymers are insulators of heat and electricity, can be flexible and can be easily moulded.
• The properties of composites depend on the matrix or binder, and the reinforcement.
• Alloys are mixtures of metals that have been mixed with other elements to make them stronger.
• Types of steel (iron alloys)

  • low carbon (0.1-0.3%) - can be easily shaped, use for car bodies
  • high carbon (0.22-2.5%) - very hard and inflexible, use for blades for cutting tools and bridges
  • stainless steel (chromium is added, and sometimes nickel) - corrosion resistance, use for cutlery and containers for corrosive substances
• Bronze


  Copper + tin - harder than copper, and used for medals, decorative ornaments and statues.
• Brass


  Copper + zinc - more malleable than bronze and is used where low friction is required, such as in water taps
• Gold alloys


  Pure gold is very soft, so metals such as zinc, copper and silver are used to harden it. Pure gold is 24 carat, so 18 carats is 75% gold.
• Aluminium alloys


  Aluminium has a low density which is good for aircraft manufacture. But pure aluminium is too soft.
• Corrosion is where metals react with substances in their environment and are gradually destroyed. Iron corrodes easily - it rusts. For iron to corrode, it needs oxygen and water
• Corrosion only happens on the surface when it is exposed to air.
• To show water alone can't rust iron, you can put an iron nail in a boiling tube with just water.

  
• You can put an iron nail in a boiling tube with no water and just oxygen, and the nail won't rust.

  A) calcium chloride

  
• How to prevent rusting

  • painting or coating with plastic
  • electroplating - uses electrolysis to reduce metal ions onto iron electrode. Can coat iron in a different metal
  • oiling or greasing
  • galvanising - sacrificial method, where an object is coated with another metal
• Renewable sources reform at a similar rate than we use them. However, this is not the case for non-renewable sources.
• Mining metal ores is good because useful products can be made, provides people with jobs and brings money into the area. However, it is bad for the environment as it uses a lot of energy, ruins the landscape, produces a lot of waste and destroys habitats.
• Sustainable development is development that meets the needs of the present without damaging the lives of future generations.
• As well as using them, extracting resources can be unsustainable due to the amount of energy used and waste produced.
• One way to improve copper's sustainability is extracting it from low grade ores using:

  • bioleaching
  • phytomining
• Bioleaching


  Bacteria are used to convert copper compounds in the ore into soluble copper compounds, separating the copper from the ore in the process. The leachate (solution) contains copper ions which can be extracted using electrolysis or displacement.
• Phytomining


  Involves growing plants in soil containing copper. Plants can't use or get rid of the copper, so it builds up in the leaves. Plants can be harvested, dried and burned, so the ash contains soluble copper compounds that can be extracted by electrolysis or displacement.
• Recycling metals uses less energy than is needed to mine a new metal, conserves the finite amount of each metal and cuts down on waste sent to the landfill
• Metals are usually recycled melting them and casting them into the shape of the new product.
• Glass bottles can already be reused without reshaping. Some forms have to recycled - glass is separated by colour and chemical composition, crushed and melted to reshape.
• A life cycle assessment (LCA) is a method of assessing the environmental impacts of a product or service throughout its life cycle. Stages to consider are:

  1. getting the raw materials
  2. manufacturing and packaging
  3. using product
  4. product disposal
• Getting the raw materials

  Extracting raw materials can damage the environment and can cause pollution. They often need to be processed to extract the desired materials, which requires a lot of energy.
• Manufacturing and packaging


  Manufacturing and packaging products can cause a lot of pollution - like harmful fumes such as CO. Waste produced and how to dispose of it needs to be considered.
• Using the product


  The use of a product can damage the environment e.g. burning fuels, fertilisers leaking into rivers. How long a product is used for and how many uses as well.
• Product disposal


  Many products are disposed of in landfills, which takes up space and pollutes land. Energy used to transport waste to landfill, which releases pollutants. Products might be incinerated, causing air pollution.