C10 Flashcards
What do humans use Earth’s resources for?
Warmth; shelter; food and transport
What do natural resources provide?
Food, timber, clothing and fuels
What’s the difference between finite and renewable resources?
Finite means the resource will run out. The rate it is use is faster than it is being made. Renewable is the opposite.
What is potable water?
Water that is safe to drink (not necessarily pure water as it contains dissolved substances)
How is potable water produced in the UK? (3)
- Choosing an appropriate source of freshwater e.g. lakes. 2. Filtration - filter the solids out through filter beds. 3. Sterilising to kill any harmful bacteria - using ozone; UV light or chlorine.
How is potable water produced in other countries where freshwater is limited and why is it harder?
Desalination by distillation or reverse osmosis of salty water. It requires much more energy which is much more expensive.
Required practical 8 - pure water.
- Check pH of water using universal indicator to test for dissolved acids or alkalis. 2. To test for other dissolved things: Weigh an evaporating basin with scales. 3. Fill with water and place on tripod over Bunsen burner. 4. Gently heat until water has evaporated. 5. If the mass increases then there are dissolved solids because they now crystallise whilst the water has gone.
What are some examples of sewage?
- Home activities like baths and toilets. 2. Industrial processes like the Haber process. 3. Sewage from agriculture.
How does sewage treatment work? (5)
- The sewage is screened to remove any solid bit. 2. Sedimentation - heavier sludge goes to the bottom whilst the effluent floats on top. 3. Effluent is removed by aerobic digestion. 4. Sludge is broken down by anaerobic digestion. 5. Methane gas released from sludge can be used as an energy source while the rest can be a fertiliser.
What are 2 ways to extract low grade copper ores?
Phytomining and bioleaching
What does phytomining do?
Phytomining uses plants to absorb metal compounds from the soil. The plants are harvested and then burned to produce ash that contains the metal compounds.
What does bioleaching do?
Bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
What is another way to get copper?
Displacement or electrolysis
What is a life cycle assessment?
Looks at every stage of a products life to assess the impact it would have on the environment
What are the 4 stages of a life cycle assessment?
1) Getting the raw materials 2) Manufacture and packaging 3) Using the product 4) Product disposal
Compare the life cycle assessments for a plastic vs paper bag.
Plastic: made of crude oil (non renewable); fractional distillation and cracking and polymerisation and less waste; can be reused; recyclable but no biodegradable. Paper: made of timber; lots of waste made; only used once; biodegradable; non toxic and can be recycled.
What is corrosion?
The destruction of materials by chemical reactions with substances in the environment.
What is an example of corrosion?
rust
What does iron need so it can rust?
Air and water
How can corrosion be prevented?
By applying a coating that acts as a barrier such as greasing, painting electroplating (coating the material with a metal). OR Sacrificial protection.
What is an example of corrosion be prevented?
Aluminium has an oxide coating that protects the metal from further corrosion.
What is sacrificial protection?
Where a metal, for example iron, is coated in another more reactive metal, such as zinc, that will oxidise more readily protecting the iron from corrosion. The layer is simply replaced when it has corroded.
What is the alloy bronze made up of?
Copper and tin.
What is the alloy brass made up of?
Copper and zinc.
What is 24 carat and 18 carat gold?
24 carat is fully gold and 18 carat is 75% gold.
What is steel made up of?
Iron and others like carbon.
What is high carbon and low carbon steel like?
High - strong but brittle. Low - softer and more easily shaped.
What type of steel is hard and resistant to corrosion?
Stainless steel - contains chromium and nickel
What type of density do aluminium alloys have?
Low
What can we use to reduce waste and environmental impacts?
Reuse, reduce our use, recycle
What are some things which are produced from limited raw materials?
Metals. Glass. Building materials. Clay ceramics and most plastic.
What is something which can be recycled?
Glass bottles can be crushed and melted to make other glass products.
How can metals be recycled and what is an example?
Recycled by melting and recasting or reforming into different products. Amount of separation required for recycling depends on the materials and their properties. E.g. some scrap steel can be added to iron to from a blast furnace to reduce amount of iron extracted from iron core.
What is most glass made of?
Soda - lime glass; made by heating a mixture of sand; sodium carbonate and limestone.
What is another type of glass?
Borosilicate glass; made from sand and boron trioxide. It melts at a higher temperature than soda - lime glass.
What do thermosoftening polymers do when heated?
They melt.
What do thermosetting polymers do when heated?
They do not melt.
How is low and high density produced from ethene and what are some examples?
Low - made from ethene at a moderate temperature but a high pressure. Flexible so used for bottles and bags. High - lower temperature and lower pressure and a catalyst. More rigid so used for drainpipes.
What’s the difference between thermosoftening and thermosetting in terms of their structure?
Thermosoftening contains individual polymers entwined together with weak forces. Thermosetting contain monomers that for cross links between polymers and chains; holding them together in a solid structure.
What is a composite?
Most composites are made of two materials, a matrix or binder surrounding and binding together fibres or fragments of the other material - called a reinforcement.
What are some examples of composites?
Fibreglass; carbon fibre; concrete; wood
What does the Haber process produce?
Ammonia which can be used to produce nitrogen based fertilisers.
What are the raw materials for the Haber process?
Nitrogen from the air and Hydrogen from natural gas
How does the Haber process work?
- Nitrogen and hydrogen are passed over an iron catalyst at around 450*c and 200 atmospheres of pressure. 2. Some of the hydrogen and nitrogen react to form ammonia. 3. Because the reaction is reversible some of the ammonia breaks down into nitrogen and hydrogen. 4. On cooling the liquid ammonia can be removed from the mixture. 5. The unreacted nitrogen and hydrogen are recycled and reused again.
What’s the equation for the Haber process?
N2(g) + 3H2(g) = 2NH3(g)
What are the conditions needed for the Haber process and what do they do in reality and why?
- Low temperature but it means a slower rate of reaction so we actually compromise at 450 degrees. 2. High pressure but it is quite expensive and dangerous so we compromise at 200. 3. Iron catalyst speeds up the reaction but doesn’t affect the yield.
What do fertilisers actually do?
Provide the plant with the 3 elements if they are missing any. The crops grow faster and bigger.
What do NPK fertilisers contain?
Nitrogen; phosphorus; potassium
What can be mined as a source of potassium?
potassium chloride and potassium sulphate
What are the different reactions of phosphate rock?
phosphate rock with nitrate acid –> phosphoric acid + calcium nitrate. phosphate rock with sulfuric acid –> phosphoric acid calcium sulfate. phosphate rock with phophoric acid –> calcium phosphate
How is the reaction for NPK fertlisers different in industry vs the lab?
In industry: reaction is carried out in large tubs; exothermic reaction and is very concentrated. In the lab: reaction is a smaller scale with titrations and crystallistation. Low concentration; less heat; more safe.
