10. Using Resources

• Earth's resources


  Natural resources that have been made without any human input, and are used for warmth, shelter, food and transport
• Warmth


  • Natural gas
  • Firewood
• Shelter


  • Stone
  • Clay
  • Sand
• Food


  • Soil
  • Fish
• Transport


  • Crude oil
  • Iron ore
• The Earth's natural resources are often improved by man-made processes such as agriculture and synthetic processes
• Agriculturally improved products


  • Increased crop production through fertilisers
  • Farm-raised fish supplementing wild-caught fish
  • Managed timber plantations supplementing natural forests
  • Cotton and hemp fabrics supplementing natural wool and silk
  • Biofuels and biodiesel supplementing or replacing petroleum fuels
• Synthetically improved products


  • Polyester supplementing natural cotton
  • Synthetic rubber supplementing or replacing natural rubber
  • Synthetic leather supplementing or replacing natural leather
  • Engineered wood products supplementing natural wood
• Finite resources


  Resources that will eventually run out, like fossil fuels, metal ores and minerals
• Renewable resources


  Resources that can replenish naturally over time, like solar energy, wind energy, and wood from managed forests
• Role of chemistry


  • Improving agricultural processes through fertilisers and pesticides
  • Creating sustainable materials that meet our needs while ensuring future generations can also meet theirs
• Sustainable development


  A developmental approach that considers the long-term impact on the environment, with the goal of creating products that fulfil our current needs without depleting resources or harming the environment for future generations
• Potable water


  Water that's safe to drink, containing very low levels of dissolved salts and microbes, and free from harmful chemical substances
• Potable water is not the same as pure water, which only contains H2O molecules, whereas potable water can include various dissolved substances
• Producing potable water from fresh water


  1. Choosing water sources with low levels of dissolved substances

  2. Passing water through filter beds to remove solid particles

  3. Sterilising the water with agents like chlorine, ozone, or UV light
• Desalination


  The process of removing salts from salty water or sea water to make them potable
• Desalination methods


  1. Distillation: Boiling water to create steam and then condensing it back into liquid, leaving the salts behind

  2. Reverse osmosis: Using a membrane that allows water particles to pass through but not salt ions, separating them
• Desalination processes typically require a lot of energy and are expensive
• Finding the amount of dissolved solids in a water sample

  1. Record the mass of a dry evaporating basin

  2. Pour a known volume of the water sample into the evaporating basin

  3. Heat the evaporating basin until its mass stays constant (all the water has evaporated)

  4. Record the mass of the evaporating basin and contents, and subtract the initial mass to get the mass of the dissolved solids
• Purifying water using distillation


  1. Add the water sample to the boiling flask

  2. Heat the water using the Bunsen burner until boiling occurs

  3. The water vapour will pass through the condenser and condense

  4. The distilled water will collect in the beaker
• The purified water can be analysed by checking the pH and boiling point
• Waste water


  Water from household activities, agricultural runoff, and industrial processes that must be treated before being returned to the environment
• Sewage treatment process


  1. Screening & grit removal: Removing large objects

  2. Sedimentation: Allowing heavy solids to settle as sludge while lighter substances float as effluent

  3. Aerobic biological treatment: Treating effluent with aerobic bacteria that consume organic matter

  4. Anaerobic digestion: Breaking down sludge with bacteria in a no-oxygen environment, producing methane and fertilisers
• Additional treatment is necessary for water contaminated with hazardous chemicals, which may include UV radiation or membrane filtration
• Sewage treatment requires more processes than treating fresh water but uses less energy than desalination of salt water, so could be used as an alternative in areas where there's not much fresh water
• Phytomining


  Using plants to absorb metal compounds from the soil, then harvesting and burning the plants to produce ash containing the metal compounds
• Bioleaching


  Using bacteria to extract metals by producing leachate solutions that contain the metal compounds
• Extracting metals from phytomining or bioleaching


  1. Dissolving the metal compounds in acid

  2. Extracting the pure metal by displacement or electrolysis
• Life cycle assessment (LCA)


  A method to evaluate the environmental impact of a product through all stages of its life, including extracting and processing raw materials, manufacturing and packaging, use and operation, and disposal
• LCAs can quantify factors like water usage, resource consumption, energy sources, and waste production, but some effects like pollutant effects involve more subjective measurements
• Abbreviated or selective LCAs


  Simplified versions of LCAs that may not include all stages of the lifecycle or may focus on specific aspects of environmental impact, but must be used carefully to avoid misleading conclusions
• Reduction, reuse, and recycling (the 3 R's)


  Key strategies in conserving resources and minimising waste
• POLLUTANT EFFECTS


  More complex, involves subjective measurements based on a person's judgement
• Bias


  Can lead to subjective measurements
• Abbreviated LCAs


  Simplified versions of LCAs that may not include all stages of the lifecycle or may focus on specific aspects of environmental impact
• Abbreviated or selective LCAs must be used carefully to avoid misleading conclusions, especially in advertising
• Reduction


  The most effective way to minimise waste is to not create it in the first place
• Reuse


  Before throwing things away, consider if they can serve another purpose
• Recycling


  Transforming used materials into new products is essential for reducing the need for raw resources and the energy used in production processes
• The 3 R's


  • Reduction
  • Reuse
  • Recycling