Topic 10: Using Resources Flashcards
What is sustainable development?
Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
In the UK, potable (safe to drink) water is produced by…?
• choosing an appropriate source of fresh water
• passing the water through filter beds to remove any solids
• sterilising to kill microbes
What are the sterilising agents for potable water?
Sterilising agents used for potable water include chlorine, ozone or ultraviolet light.
• Chlorine is a toxic gas so the amount added to water has to be carefully monitored.
• Using ultraviolet light to kill microbes avoids adding chemicals to the water but is more expensive
How is desalination carried out?
- Desalination methods: distillation and membrane processes (e.g., reverse osmosis).
- Both methods are energy-intensive.
What is reverse osmosis?
- Seawater is filtered through a membrane that permits only water molecules.
- High pressure is essential to push water through the membrane.
- Producing the high pressure demands substantial energy.
How is wastewater produced and how is it treated?
- Urban and industrial activities generate substantial wastewater needing treatment.
- Sewage and agricultural wastewater must have organic matter and harmful microbes removed.
- Industrial wastewater needs the removal of organic matter and harmful chemicals.
What are the processes involved in sewage treatment?
Sewage treatment includes:
- screening and grit removal
- sedimentation to produce sewage sludge and effluent
- anaerobic digestion of sewage sludge
- aerobic biological treatment of effluent
What do new methods of mining avoid in terms of disadvantages of traditional mining?
Avoids the disadvantages of traditional mining methods of digging, moving and disposing of large amounts of rock
What is phytomining?
- Phytomining involves plants absorbing metal compounds from soil.
- Plants are harvested after absorbing metals.
- Harvested plants are burned to produce ash.
- Ash contains the metal compounds extracted by the plants.
What is bioleaching?
Bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
What are the main advantages and disadvantages of phytomining and bioleaching?
These methods need less energy than traditional methods, and can work on low concentration ores but are slow to carry out.
Describe the stages of LCAs
Life Cycle Assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages:
- extracting and processing raw materials
- manufacturing and packaging
- use and operation during its lifetime
- disposal at the end of its useful life, including transport and distribution at each stage.
How do we reduce the use of resources?
The reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, energy consumption, waste and environmental impacts.
What are the advantages and disadvantages of recycling?
- Advantages of recycling: less acid rain (pollution) metal ore reserves last longer / conserved energy for extraction saved less mining / quarrying less waste less landfill creates local employment
- Disadvantages of recycling: collection problems transport problems/ cost of transport difficult to separate metal from appliances/sort
What is corrosion and how is it prevented?
- Corrosion Definition: Destruction of materials by chemical reactions with environmental substances (e.g., rusting).
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Prevention Methods:
- Apply a coating to act as a barrier.
- Common coatings: greasing, painting, electroplating.
- Purpose: Prevent air or water from contacting the metal.
Describe the sacrificial protection
- Reactive coatings can include corrosion inhibitors or a more reactive metal.
- When two metals are in contact, the more reactive metal corrodes, protecting the less reactive one.
- Example: Zinc galvanizes iron; if scratched, zinc corrodes instead of iron due to its higher reactivity, offering sacrificial protection.
Describe the compounds and the uses of bronze, brass, gold and silver and copper and zinc, aluminium-magnesium and steels
Alloys:
- Bronze: Alloy of copper and tin; used for statues and decorative objects.
- Brass: Alloy of copper and zinc; used for water taps and door fittings.
- Gold Jewelry: Usually alloyed with silver, copper, and zinc; purity measured in carats (24 carat = pure gold, 18 carat = 75% gold).
- Aluminium-Magnesium Alloys: Low density; used in aerospace manufacturing.
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Steels:
- High carbon steel: Strong but brittle.
- Low carbon steel: Softer and more easily shaped.
- Stainless steels: Contain chromium and nickel; hard and resistant to corrosion.
How are the properties of polymers determined?
- Polymer properties depend on the monomers used and the manufacturing conditions.
- Example: Low Density (LD) and High Density (HD) poly(ethene) are both made from ethene.
- Different catalysts and reaction conditions produce LD and HD poly(ethene).
Describe the structures of thermosoftening and thermosetting polymers
- Thermosetting polymers:
- Do not melt on heating.
- Linked by strong cross-links.
- Thermosoftening polymers:
- Soften easily on heating.
- Can be remoulded.
- Maintain new shape on cooling.
- Attracted by weak intermolecular forces.
How is glass made?
- Most common glass: soda-lime, made from sand, sodium carbonate, and limestone.
- Borosilicate glass: made from sand and boron trioxide.
- Borosilicate glass has a higher melting point than soda-lime glass.
How are clay ceramics made?
Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace.
How are composites formed?
- Reinforcement: Fibers or fragments of a material.
- Binder/Matrix: Surrounds and holds fibers/fragments together.
- Example: Fiberglass - glass fibers in polymer.
- Usage: Making storage tanks.
Outline the key points of Haber process. Include the use of the product.
- Purified H2 and N2 gases pass over Fe catalyst at high temp (450°C) and pressure (200 atm)
- Fe catalyst accelerates reaction rate, enabling lower temp usage
- Reaction: N2 + 3 H2 ⇌ 2 NH3
- Reaction is reversible; NH3 breaks down into N2 and H2
- Cooling liquefies NH3, removed; H2 and N2 recycled, minimal waste
- NH3 used for nitrogen-containing fertilizers
The Haber process operates at high T, p conditions. Explain why this is so and why this is a compromise.
- Reaction is exothermic, optimized at 450°C
- Lower temperature = higher yield but slower rate of NH3 production
- Pressure set at 200 atm
- Higher pressure = higher yield, but costly due to energy expense
