Chapter 14 - The Earth's Resources Flashcards
What are the examples of finite resources?
- Metal ores used to extract metals
- Crude oil used to make polymers
- Limestone used to make concrete and cement
- Crude oil to make fuels
Why can poly (ethene) be sustainable?
Ethanol can be made by fermenting glucose from sugar cane or sugar beet. So a renewable crop can be used to make poly (ethene), rather than using crude oil.
Give three examples of natural resources that are supplemented, or replaced by synthetic products
- Wool —-> Acrylic Fibre and Poly (Propene)
- Cotton —-> Polyester
- Silk —-> Nylon
What is the difference between Potable water and Pure water?
Potable water is safe for humans to drink, so it has low levels of dissolved salts or minerals, and no microbes. Pure water has no impurities, including minerals.
How is potable water collected from ground water?
- Water passes through a screen to catch large objects like leaves or twigs.
- Goes into a sediment tank, where sand and soil settles at the bottom
- Aluminium Sulphate and Lime is added, to get rid of any remaining solid particles
- Passes through filter made of fine sand and gravel to remove any mud or grit
- Add chlorine to kill the bacteria (can also use ozone or UV light)
- pH is checked to make sure it’s neutral
Describe a required practical where you analyse and purify water samples.
- Check the pH of the water sample, by using universal indicator
- Use a balance to weigh the mass of an empty evaporating basin
- Fill the evaporating basin with a water sample, and heat up, until it has all water has evaporated.
- If the mass has increased, then the sample contained dissolved salts
- Crystals would also form on the side
Still, if no dissolved solids were formed, then there still may be dissolved gases.
How can salty water be purified?
We can use fractional distillation. Desalination is also used, where reverse osmosis use membranes, but it is very expensive.
How is waste water treated?
- Screening and removal of grit and other solids
- Sedimentation is done to produce sewage sludge and effluent
- Sewage sludge undergoes anaerobic digestion to remove any potentially harmful microorganisms
- The effluent is undergoes aerobic biological treatment, where bacteria can feed off any harmful microorganisms
- Water can go back into the river, or it can be sterilised by using UV, ozone or chlorine.
- Sludge can be used as a fertiliser, or used in biofuels
What are the 2 main ways to extract copper from low grade ores?
Phytomining and Bioleaching
What is phytomining?
Phytomining uses plants to absorb metal compounds. The plants are then harvested and burned to produce ash that contains the metal compounds.
What is bioleaching?
Bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
What is an alternative way to extract copper from low grade ores?
The metal compounds can be processed to obtain the metal. For example, copper can be obtained from solutions copper compounds, by displacement using scrap iron or by electrolysis.
What are the advantages of phytomining and bioleaching?
- Removes toxic copper compounds from soil
- Mining not required
- Less waste rock
- Less energy needed
What are the disadvantages of phytomining and bioleaching?
- It is very slow
2. Copper compounds still need to be purified via displacement or electrolysis
What are Life Cycle Impacts?
They are assessments carried out to analyse the environmental impact in each of these stages:
- Extraction and processing of raw materials
- Manufacturing and production
- Use and operation during lifetime
- Disposal
