Unit 10: Using Resources

• Sustainable development


  An approach on development that takes into accounts the needs of present society while not damaging the lives of future generations.
• Unsustainable development examples & what can chemists do to produce more sustainable developments

  - A lot of resources are non-renewable, so using these finite resources would be unsustainable.

  - Extracting and processing resources can take up huge amounts of energy and create waste, so this is unsustainable.

  
  

  We can't fully stop using finite resources, but chemists can produce processes which will reduce the energy use and waste produced, creating more sustainable processes.
• state examples of natural products that are supplemented or replaced by agricultural and synthetic products

  Excrements used to be used by farmers to fertilise their fields, now fertilisers are used which are created by the Haber process.
• finite vs natural (pros and cons) (5)

  constantly renewed, can run out

  requires large area, requires small area

  large infrastructures, can be found in many countries

  natural from the earth, coal extracted

  high initial cost, low initial cost
• potable water


  water that is safe to drink, not to be confused with pure water, which contains only H2O molecules, and potable water can contain other dissolved substances.
• give reasons for the steps used to produce potable water in the uk

  1. sedimentation - large particles sink to the bottom and are removed.

  
  

  2. filtration - water is passed through a large wired mesh to remove any large particles like twigs and then is passed through sand or gravel beds to remove any more solid particles.

  
  

  3- sterilisation - the water is sterilised to get rid of any harmful microbes or bacteria, this is done so by bulbbing chlorine gas through it or using ozone or ultra violet light.
• describe the differences in treatment of ground water and salty water

  Ground water is turned into potable water through three steps. The first one is sedimentation, where large particles are removed from the water. Then, it passes to the second stage, filtration where first a large wired mesh is used to remove any large particles, such as twigs and then gravel and Sandbeds are used to remove any more solid particles. Then it goes into the third step, which is sterilisation in which harmful bacteria and microbes are sterilised. This is done through the bubbling of chlorine gas through the water or using ozone or ultraviolet light. salty water can be turned into principal water two different ways. One is desolation which is done so through distillation. The second method is reverse osmosis, in which water can be passed through a membrane where only water particles can pass through ions and large molecules are separated from the water. both desalinisation and reverses, osmosis are expensive processes which require large amounts of energy.
• Required Practical 8: analysis and purification of water samples from different sources, including pH, dissolved solids and distillation.


  First, the student should analyse a sample of water.

  1) Use a universal indicator to measure the pH of the water.

  2) measure and record the mass of an empty evaporating dish.

  3) pour 10cm3 of water into the evaporating dish. Evaporate the water using a bunsen burner, until most of the water has been evaporated.

  4) once the evaporating dish is cooled, reweigh and measure the mass of the dish. record your results.

  5) calculate the mass of the dissolved solids in the water.

  Secondly, to purify the sample of water using distillation, the student should:

  1) pour a sample of water into a conical flask and set up the apparatus for distillation.

  2) Gently heat up the solution using a bunsen burner. Then, turn down the heat so that the water boils gently.

  3) Collect around 1cm3 of water in the cooled test tube, then turn the bunsen burner off.

  4) Analyse the sample of distilled water using cobalt chloride paper.
• waste water comes from lots of different sources

  urban lifestyle and industrial processes can produce huge amounts of waste water that need to be collected and treated before being released into the environment and other water sources
• examples of urban lifestyle and industrial processes that produce waste water

  - domestic/agricultural waste produces waste water which contains harmful microbes and bacteria which needs to be treated and conserved before it can be put back into other water sources.

  - industrial processes produce huge amounts of waste water (haber process) that has to be treated and conserved before it can be put back into other water sources. it can also cause harmful microbes.
• Waste water treatment


  The first step is screening and grit removal. Before being treated, the water is screened to get rid of any large objects (twigs or plastic bags etc) and to remove any grit from it.

  Then, its allowed to stand in a settlement tank, where sedimentation takes place - the heavier suspended solids make sludge at the bottom of the tank whereas the lighter effluent floats on top.

  The effluent at the top of the settlement tank is removed using biological aerobic digestion. This is where air is pumped through the water to encourage aerobic bacteria to break down any organic matter - including the microbes in water.

  The sludge from the bottom of the settlement tank is removed to be placed in other large tanks. Organic matter and microbes are released from sludge through anaerobic digestion, which releases methane gas in the process of breaking down organic matter. The methane gas is used as an energy source and the remaining DIGESTED WATER can be used to produce fertilisers.

  For waste water containing toxic waste, further processes can be used like using chemicals, UV radiation and membranes.
• Explain why Cu-rich ores are in short supply

  Copper is a finite resource, and so there isn't many Cu - rich ores left. One way to improve its sustainability is by extracting Cu from low grade ores.
• Bioleaching


  A process of extraction of metals in which bacteria is used to produce copper compounds in the ore into soluble Cu compounds, and so the Cu is separated from the ore in the process. It can be extracted using electrolysis or displacement, using a metal with a higher reactivity.
• Phytomining


  a process of extraction of metals from ores using plants, in which plants are grown inside Cu rich soil. The plants cannot dispose of or use the Cu, so it grows into the leaves. The leaves can then be harvested, dried and burnt using a furnace. Cu will be inside the ash, and so Cu can be extracted by using electrolysis or displacement, using SCRAP FE.
• LCA


  A LCA looks at every stage in a product's life to see what impact it would have on the environment.
• LCA Stage 1


  Getting the raw materials:

  1) Extracting raw materials can be damaging to the local environment and can result in pollution due to the amount of energy needed to extract raw materials.

  2) Raw materials often need to be processed to extract desired materials, this can release huge amounts of energy.
• LCA Stage 2


  Manufacturing and packaging:

  1) Manufacturing and packaging of products can use huge amounts of energy and can cause a lot of pollution (eg CO fumes)

  2) Chemical reactions used to make compounds from their raw materials can produce waste products. Some waste can be turned into useful chemicals, reducing the amount that ends up polluting the environment.
• LCA Stage 3


  Using the Product:

  1) The use of a product can cause damage, for example the burning of fossil fuels causes greenhouse gases, fertilisers can leach into water sources.

  2) How long a product is used for or how many uses a product has can also be measures, e.g. a product which takes up huge amounts of energy to process but can be used for many years may not be as damaging.
• LCA Stage 4


  Product disposal:

  1) Products are often disposed of in landfills, which takes up space and can damage the environment.

  2) Products also need to be transported to landfills, producing pollution (e.g. fumes)

  3) Products may also be incinerated, causing air pollution.
• problems with LCA's


  1) The use of energy, natural resources and amount of waste a product produces in its lifetime can be easily quantified, however the amount of pollutants a product releases is much harder to do.

  2) So, LCA's can be biased, as it is an objective method which takes into accounts the needs of the assessor.

  3) selective LCA's only show SOME of the impacts of the product on the environment, and so are biased as LCA's can be deliberately written to support a companies product, for positive advertising.
• Plastic VS Paper Bag

  
• Why is recycling metals important?

  Extracting and mining metals take huge amounts of energy. Recycling metals:

  1) Uses less energy than is needed to mine & extract new metals

  2) Conserves the finite amount of each metal in the earth

  3) Cuts down on the amount of waste getting sent to landfill
• The amount of separation to recycle a metal depends on

  the material and the properties of the final product (e.g waste steel and iron can be burnt in a blast furnace to reduce iron extracted from iron ores.)
• glass can also be recycled


  Reusing or recycling glass can reduce energy needed to make new products. Glass bottles can be reused, but other glass objects will need reshaping:

  1. Glass is separated into colour and chemical composition

  2. Glass is melted and reshaped to make new jars and glasses, but can also be re-shaped for other purposes like insulating glass wool.
• corrosion


  The destruction of materials by chemical reactions with substances in the environment
• rust equation


  iron + water + oxygen --> hydrated iron (III) oxide
• Corrosion on Fe materials

  When Fe corrodes only the surface exposed to air will begin to rust. However, rust on Fe materials will eventually flake off, exposing more material of Fe, until the whole objects corrodes
• corrosion on aluminium


  Opposite to Fe, ALO is formed when Al is exposed to corrosion, which forms a layer on the top of the surface which won't cause the rust to flake, creating a protective layer on the Al
• Students should be able to describe experiments and interpret results to show that both air and water are necessary for rusting


  To ensure that H2O isn't enough by itself, place an iron nail inside a boiling tube filled with water, no O2. Pour oil to ensure no O2 comes in. The nail won't rust.

  To ensure that O2 isn't enough on it's own, place an Fe nail inside a boiling tube with just air in it. Place CaCl inside to ensure no H2O enters. The nail won't rust.

  A Fe nail will rust when it is placed inside a boiling tube with water and O2.
• How can corrosion be prevented (coating)

  1. Coating:

  - Painting/coating with plastic; ideal for big/small structures and can be decorative too.

  - Electroplating; Electrolysis used to remove Fe ions from Fe, can be done by coating the Fe in another metal that won't corrode.

  - Oiling/greasing: Has to be done for materials which are moving, like bike chains
• How can corrosion be prevented (sacrificial method)

  2. Sacrificial method:

  Where a more reactive metal like Zn or Mg is placed on top of Fe, so that when exposed to corrosion, the sacrificial method will corrode.

  - Galvanising - Spraying an object with Zn, so at first Zn will act like a protective layer and once scratched will become a sacrificial method
• Alloys


  Alloys are made by adding another element to a metal, altering its structure and so making alloys stronger than metals. Most metals in everyday uses are alloys.
• Brass


  An alloy of copper and zinc, used for objects that require less friction, like water taps or door fillings
• Bronze


  Alloy of copper and tin, used for medals, decorating ornaments, statues.
• Gold


  Alloy of silver, copper and zinc used for jewellery. Measured in carats, 24 carats would be 100% gold, 18 carats 75% gold.
• Aluminium alloy


  Have a low density, used for aircraft. Pure Al is too soft to use in aircrafts so is alloyed with metals to make it stronger and suitable.
• Steel


  An alloy made of different levels of copper and other metals. High carbon steel is strong but brittle, low carbon steel is softer and easily shaped. Stainless steel is made out of chromium and nickel, hard and resistant to corrosion. Used to make cutting tools/blades
• Ceramic


  Non metal solids with high boiling points that are not made from carbon-based compounds
• Clay


  A ceramic which is a soft material when dug out the ground, making it easy to mould into shapes. it is then blasted by heat, and so dried. Ideal for bricks/pottery.
• Glass


  Transparent but brittle, which can be moulded when hot and then cooled down to form glass.

  - Soda-lime glass: A mixture of sand, limestone and sodium carbonate which is heated and then let cool down, to form glass.

  - Borosilicate glass: Same method as soda-lime but with higher temperatures required and a different mixture, sand and BORON TRIOXIDE