- Created by: AMcL1
- Created on: 30-05-19 12:38
- Finite/Non-Renewable Resource - This is the name given to a resource that is running out and there is only a limited amount of. Finite resources are used at a faster rate than the rate at which they are produced. Examples of finite resources include metal ores, limestone and fossil fuels.
- Renewable/Infinite Resource - This is the name given to a resource that can be replaced. This means that it is being used at a fast rate, but it takes less time to be produced, and so the supply is keeping up with the demand. Examples of renewable resources include plants and biofuels.
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Water Safe to Drink
- Potable Water - This is made by the following process: Firstly, the water if filtered. Then, it is transported to a settlement tank, where aluminium sulfate and limewater are added. These chemicals cause dirt to clump together and sink to the bottom. Lastly, chlorine, ozone or UV are added to kill bacteria. This makes the water safe to use.
- Purifying Salty Water - In order to purify salty water, two processes can be used. Desalination through distillation is possible, however this can be expensive and may require lots of energy. The other possible process is reverse osmosis, which uses a partially permeable membrane to separate pure water molecules from the salt. There are disadvantages of this method though, including that it requires lots of energy and high pressures to produce a small amount of pure water. This makes it expensive and less efficient that other processes.
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Treating Waste Water
- The first element of the waste water treatment process is screening. This helps to remove large pieces of solid and grit.
- Then, primary treatment takes place. This is where sedimentation happens and sewage sludge is made.
- After this, it is secondary treatment, where bacteria are added to the sewage sludge to feed on organic matter,
- Lastly, the waste water goes through final treatment, where the bacteria are separated and the water is released.
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Extracting Metals From Ores
- Many different methods are used to extract metals from their ores, including smelting, electrolysis, displacement, using sulfuric acid, phytomining and bioleaching. These processes are described below.
- Smelting - This is where the ore (usually a copper one) is heated to a high temperature using carbon. The product of smelting is usually impure though, for example, it produces copper that is only 80% pure.
- Electrolysis - This creates a purer product but uses lots of energy, so is quite expensive.
- Displacement - This is where a more reactive metal can be used to displace the less reactive metal from its ore.
- Using Sulfuric Acid - This method creates copper sulfate, from which the copper can then be extracted from.
- Phytomining - This method describes using plants to collect copper. First, the plants are grown, then they are burned and this burning is used to extract the copper.
- Bioleaching - This is where bacteria feed on a low grade ore to help separate the metal from the rock.
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Life Cycle Assessments
- Life Cycle Assessments (LCAs) assess only the environmental impact of products, processes or services.
- The process of carrying out an LCA has many stages. Firstly, they assess the environmental impact of the raw material extraction, then the manufacturing of the product, and after that, the use, reuse or maintenance of the product. The fourth and final stage in the assessment process looks at the environmental impact of the recycling or waste management of the product.
- One problem that surrounds the use of LCAs is that assigning numerical values to the product, process or service is subjective, so may be inaccurate.
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Reduce, Reuse, Recycle
- There are many social, economic and environmental issues with exploited resources, and so this campaign helps to raise awareness of these and try to limit and prevent them.
- This scheme also helps to reduce pollution caused by mining and extraction, as the smae materials are used again.
- Recycling is the main element of this campaign. It is important as it saves energy and saves limited, finite ores.
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- Rusting occurs when air (oxygen) and water react with iron. There are two ways in which iron can be protected from rusting. They are described below.
- Being Galvanised - Iron can be galvanised for protection. This creates a barrier between the iron and oxygen/water so that it doesn't rust. Materials that can be used to galvanise iron include paint, oil/grease or plastic.
- Sacrificial Protection - This is where a more reactive metal is attached to the iron, such as zinc, magnesium or aluminium. This metal then reacts with the oxygen or water instead of the iron, therefore protecting it from rusting.
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- These alloys are harder than pure metals as they are made up of different size atoms and their layers are distorted. These mixtures of metals and their improved characteristics are what make them more useful.
- An example of a useful alloy is steel. This is produced carefully under controlled conditions, where carbon is added to iron. Different steel alloys have different properties. For example, steel with high amounts of carbon is very hard, but also quite brittle. However, steel with low amounts of carbon is softer and can be easily shaped. Another type is stainless steel, which is used to make cutlery. This form of the alloy is resistant to corrosion.
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- Polymers are made up of many monomers. The conditions needed to make polymers include high temperatures and high pressures.
- Polymers with a high density are made under extremely high pressures.
- Polymers with a low density are made using a catalyst at a temperature of approximately 50 degrees celsius.
- Thermosetting - Thermosetting polymers don't soften when heated. They have strong intermolecular forces and cross-links, meaning that they don't melt easily, even under high temperatures.
- Thermosoftening - Thermosoftening polymers soften when they are heated as they have weak intermolecular forces and no cross-links. This means that less energy is needed to overcome forces because they aren't very strong.
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Composites, Glass & Ceramics
- Composites - These are made of two materials, where one acts as a binder. They are made to help improve a desirable property that neither material would have individually.
- Glass - Glass is made up of borosilicate and soda. The borosilicate melts at a higher temperature and is produced from sand and boron trioxide. Soda is composed of heating sand, limestone and sodium carbonate. Both materials are then combined under extremely high temperatures to form glass.
- Ceramics - Ceramics are made from shaping wet clay and then immediately being heated strongly in a furnace.
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The Haber Process
- This is a reversible process used to recycle unreacted hydrogen or nitrogen. The product of The Haber Process is ammonia, which is cooled so that it liquifies and separates.
- The process reacts nitrogen gas (from the air) with hydrogen gas (from methane) to produce ammonia gas, using an iron catalyst. The reaction takes place under a pressure of 200 atmospheres and a temperature of 450 degrees celsius.
- There are many issues surrounding the economics of The Haber Process. For example, if the temperature was lowered, it would be cheaper, but there would be a slower rate of reaction meaning that it would be inefficient and would take too long. In addition to this, the yield could be increased by using a higher pressure, but this is too expensive to build and run. However, there are some positives, for example, one method that is cheaper and helps to speed up the reaction is using an iron catalyst.
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- Fertilisers help to supply nitrogen, phosphorus and potassium to plants.
- In the lab, ammonia is reacted with sulfuric, phosphoric or nitric acid to produce ammonium sulfate, ammonium phosphate or ammonium nitrate.
- In industry, the potassium added to fertilisers is extracted from potassium salts and the phosphorus is extracted from phosphate rock by mining it and treating it with acids.
- These elements are what combine to form fertilisers.
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