Chemistry chapter C12

• Finite resources:

  Resources that are limited
• Renewable:

  resources that can be replaced at the same rate at which they are used up
• Potable water:

  Water that is safe to drink

  Should have low levels of:

  • Dissolved salts
  • Minerals
• How to obtain potable water:

  • Rainwater dissolves some gases from the air as it falls to the ground
  • The rainwater collects underground, in lakes, in rivers
• Desalination:

  A cleaning process using distillation and reverse osmosis to remove sediment
• Reverse osmosis:

  A desalinization process that involves forcing salt-water through a membrane permeable to water but not to salt
• Process of cleansing sewage:

  1. Screening to remove large solid particles
  2. Secondary treatment (leave water to stand extremely still and the sediment drops to bottom and becomes solid sludge)
  3. Sludge is dried and anaerobically digested. Digestion of sludge produces electricity
  4. Effluent is aerobicaly digested in the presence of oxygen which removes harmful microbes
• Phytomining for copper:

  1. Plant plants in copper rich soil
  2. The copper will enter the plants through active transport
  3. Burn the plants to Ash
  4. Use bioleaching (passing a chemical through a solution to remove gas)
  5. Use electrolysis to extract the copper
• Bio leaching:

  • The extraction of specific metals from their ores through the use of bacteria
  • They do this by producing leachate solutions that contain the metal compounds that contain the metal compounds. A leachate is simply the solution we get when a liquid passes through an organism
  • Bacteria are usually used in the process
• Positives of bioleaching:

  • It is cheap
  • It is environmentally friendly
  • It can be used on ores that are poor in quality, which is important because high grade ores have a limited availability
• Negatives of bioleaching:

  • Process is very slow compared to smelting
  • There are some potentially toxic chemicals produced
  • Efficiency of the bacteria that converts the copper to copper metal is very low, so there is lots of waste
• A LCA:

  Works out the environmental impact of these stages of a products life:

  • Extraction and process of raw materials
  • Manufacturing and packaging
  • Use and reuse
  • Disposal
  • Transport and distributional stages