C6

• Ore


  A rock or mineral that contains enough metal (or metal compound) to extract, where the value of the metal must be more than the cost of extracting it
• Metal ores


  • bauxite
• Extracting metal from ore

  1. Mine the ore

  2. Process the ore to separate the metal compound from other substances

  3. Extract the metal from the pure metal compound using chemical reactions
• Extraction method


  Depends on the metal's position in the reactivity series
• All metals could be extracted from their compounds using electrolysis, but electricity is expensive
• Cheaper extraction methods


  Used for metals less reactive than carbon
• Metals less reactive than carbon


  • Copper
  • Iron
• Extracting copper from copper sulfide

  1. Stage 1: Roast copper sulfide in air to produce copper oxide and sulfur dioxide

  2. Stage 2: Heat copper oxide with carbon to produce copper and carbon dioxide
• Redox reaction


  Copper oxide loses oxygen and is reduced, carbon gains oxygen and oxidises
• Reducing agent


  Carbon acts as a reducing agent
• Reducing copper oxide


  1. Mix copper oxide and charcoal powder in a crucible

  2. Heat strongly with lid on

  3. Allow to cool

  4. Separate copper from excess charcoal
• Excess charcoal powder is used to ensure all copper oxide is reduced to copper
• Eye protection should be worn
• Extracting iron in a blast furnace

  1. Add iron ore, coke, and limestone to the top of the blast furnace

  2. Force hot air in at the bottom

  3. Carbon monoxide reduces iron(III) oxide to iron

  4. Limestone reacts with silica impurities to form slag which floats on the molten iron
• Blast furnace


  Large reaction container used to extract iron, can be around 30m high and produce 10,000 tonnes of iron per day
• Electrolysis of aluminium oxide

  1. Dissolve aluminium oxide in molten cryolite to lower the melting point

  2. Contain the molten mixture in a steel-lined graphite electrolysis cell

  3. Aluminium is produced at the cathode, oxygen at the anodes
• Aluminium is more reactive than carbon, so it must be extracted by electrolysis
• Acid mine drainage


  Metal sulfides oxidise underwater, producing sulfuric acid which reacts with other metal ores to form soluble metal compounds
• Bioleaching


  Bacteria oxidise iron and sulfide ions, producing sulfuric acid which breaks down copper sulfide and other mineral ores
• Bioleaching


  • Cheaper than traditional mining, allows extraction from low-grade ores, but is slow and can produce toxic substances
• Phytoextraction


  Plants absorb dissolved metal ions through their roots, which accumulate in the plant tissues. The plants are then harvested and burnt to extract the metal
• Phytoextraction


  • Cheaper than traditional mining, produces less waste, involves smaller energy transfers, but is slow and requires replanting and harvesting for several years
• Life-cycle assessment (LCA)


  Analysis of the impact of making, using and disposing of a manufactured product, including sustainability, environmental impact, lifespan, and disposal
• LCA data can identify stages that could be improved or alternative materials that might do the same
• Sodium is less dense than water, but it would react violently with the water
• Life-cycle assessment (LCA)


  An analysis of the impact of making, using and disposing of a manufactured product
• LCA data


  • Identify stages that could be improved, or alternative materials that might do the same
  • For example, a pair of trousers might show that 20% of the total energy used is in its production, 75% in its use, and 5% in its disposal
  • It would make little sense to try to save energy at the disposal stage, however, you could investigate how to use less energy when washing and drying since most energy is used
• Sodium is less dense than water, but it would react violently with the water and explode into flames
• You need to consider more than one property when deciding whether to use a material for a particular purpose
• Properties of three common polymers

  • Polyethene
  • PET (polyethylene terephthalate)
  • Polypropene
• Polyethene


  Cheapest, but unsuitable for drinking as boiling water will not melt it, but the cup will become too soft to hold
• PET (polyethylene terephthalate)


  Most expensive, has the highest tensile strength and melting point, but hot drinks will soften it too
• Polypropene


  Most suitable as its maximum usable temperature is above 100°C and it has a high tensile strength
• How are materials recycled?

  1. Waste materials are collected and transported to a recycling plant

  2. Sorting is usually needed at the plant, it is important to ensure that for example, glass isn't contaminated by metal bottle caps

  3. The sorted waste is then shredded or crushed into smaller pieces ready for processing

  4. Metals are melted by heating and the molten metal poured into moulds to produce new blocks called ingots

  5. Paper is mixed with water cleaned then rolled and heated to make new paper

  6. Glass is melted by heating and moulded into new glass objects

  7. Polymers like polylethene, PET and polypropene are melted and formed into new objects
• Most materials and products will end up in landfill sites as waste. Disposal like this is not an efficient use of resources
• Reasons why recycling is important


  • Conserving limited raw materials and energy resources
  • Reducing the release of harmful substances into the environment
  • Reducing waste
• Alkanes


  Hydrocarbons - compounds that contain only hydrogen atoms and carbon atoms
• Features of a homologous series

  • As you move down the series, the number of carbon atoms increases by one each time
  • The number of hydrogen atoms increases by two
  • Successive members differ by a CH group
• Making crude oil useful

  1. The alkanes in crude oil are separated from one another using fractional distillation

  2. This works because the different alkanes have different boiling points

  3. In general, the more carbon atoms there are in the alkane molecules, the larger the molecules, the stronger the intermolecular forces, the higher the boiling point

  4. Crude oil is heated and its vapours are piped into the bottom of a fractionating column

  5. This has a temperature gradient, it is hot at the bottom and cold at the top

  6. The vapours cool as they move through the column and condense to the liquid state if they reach a part that is cool enough

  7. The separated parts of the crude oil are called fractions, each fraction contains many substances with similar boiling points

  8. Bitumen has the highest boiling point, it leaves at the bottom of the column and is in the sold state at room temperature

  9. Refinery gases (methane, ethane, propane and butane) have the lowest boiling points, they reach the top and leave the column without cooling enough to condense

  10. The other fractions are in the liquid state at room temperature, they fall into trays and leave from the middle of the column
• Crude oil


  • A fossil fuel, formed from the remains of marine organisms that lived millions of years ago and became buried deep in the sea bed, where chemical reactions eventually turned them into crude oil
  • A complex mixture of hydrocarbons, mostly alkanes