Using Resources

Resources and sustainability:

Natural resources:

• What 2 things can resources can be:
  • Living
  • Non-living
• What is meant by sustainability:
  • Meeting the needs of the current generation without compromising the availability natural resources for the future generations

Renewable and Non-renewable Resources:

• What are renewable resources?
  • Resources which can be replenished or replaced faster than they are being used up
• What are non-renewable resources?
  • Resources which are being used faster then they are being produced, replenished or replaced
• Why is the extraction of resources a risk?
  • Because natural resources are finite and are being used up and extracted faster than they are being produced and so it is not sustainable
  • They require large amounts of energy to extract, which would most likely be coming from non-renewable resources such as fossil fuels

Potable water:

• What is potable water?

  • Water that has been processed and is safe for humans to drink

• What is the difference between pure and potable water?

  • Pure water is made up of only water molecules whereas potable water may contain different substances such as dissolved minerals and salts

• What are the characteristics of potable water?

  • A pH between 6.5 and 8.5
  • Dissolved substances will be present in very small regulated quantities
  • Be free of bacteria or harmful microbes

• What is surface water?

  • what which collects in reservoirs, lakes and rivers

• What is ground water?

  • water which collects in aquifers which are porous rocks that store water underground

Water treatment:

• What is meant by fresh water and examples:

  • A water source with a low concentration of dissolved substances, such as ions:
  • Examples: Spring water, surface water, aquifers

• How to process water:

  • Screen the water to remove the large objects in the water, such as tree branches
  • Filter the water to remove smaller objects such as mud and grit
  • Place the water in a sediment tank, which allows silt and sand to settle at the bottom
  • Sterilise the water with Ultra violet light, ozone or chlorine gas to kill bacteria

• When is desalination used:

  • Used to provide potable water when surface water is limited - in hot climates where the surface water has dried off

• What is desalination:

  • The process of removing salt from sea water which can occur through:
  • Distillation
  • Reverse osmosis

• Why is desalination not good:

  • It is expensive process as it uses a lot of energy, most likely coming from fossil fuels
  • Produces a low quantities of fresh water

• What is reverse osmosis:

  • Salt water and fresh water are separated using a semi-permeable membrane
  • High pressure is applied to the side with salt water
  • Only water molecules are able to pass through because large molecules and ions are too large to pass through
  • All the water molecules move to the side with the fresh water
  • In order for this water to be potable it must first be processed

Waste water treatment:

• What are the sources of waste water:

  • Domestic and urban use
  • Agricultural use
  • Industrial use

• What needs to happen to urban and agricultural waste water before they are returned to fresh water sources:

  • Needs to processed after going to sewage treatment plants to remove organic matter, kill harmful bacteria, and to remove particulates and toxins

• Why must additional treatment be in place for industrial waste water:

  • Because the water will most likely contain harmful chemicals and organic matter, and if these chemicals are placed in the environment they will harm it

• What are the 3 processes involved in sewage treatment:

  1. Screening and grit removal:
  • In this stage the large materials such as plastic bags and twigs are removed
  1. Sedimentation:
  • Occurs in a settlement tank
  • Allows the water to stand still in the tank while heavier solids sink to the bottom and settle which creates sewage sludge
  • Lighter material (effluent) floats to the top
  1. Aerobic digestion:
  • This treats effluent
  • It involves pumping oxygen into the water to encourage the breakdown of organic matter and other microbes by aerobically respiring bacteria
  1. Anaerobic Digestion:
  • Used to sewage sludge
  • It is firstly removed and placed in large tanks where bacteria break it down
  • Anaerobic digestion releases methane gas as a by produce from the organic matter in the sludge
  • This methane can then be used a fuel for energy and the leftover, digested waste as a fertiliser

• Why Sewage treatment is better than processing fresh water:

  • Although it takes longer, it uses less energy than desalination of salt water

Extracting Metals:

• How is Iron extracted:

  • Extracted from Fe2O3 (haematite)
  • Heated with Carbon in a blast furnace to displace iron

• How is Aluminium extracted:

  • Extracted from Al2O3 (bauxite)
  • Electrolysis is used, and a cryolite is added to reduce the melting point of aluminium

• How gold is extracted:

  • It is Found as the element due to low reactivity
  • No extraction is needed as it is a native metal and having a low reactivity meaning it doesn’t oxidise(react with oxygen)

• What are low-grade ores:

  • Ores with a low quantities of metal in them

• Why is mining not used to extract low grade ores:

  • Mining requires high yield of the ore to be present
  • Mining produces a lot of waste and negative environmental impacts while producing low yields

• What other methods are used to extract low-grade ores:

  • Phytomining
  • Bioleaching

• Why are other methods being used to extract low grade ores:

  • Because metal-rich ores are being used up faster than they are being made and we are running out of them

• Advantages and disadvantages of biological processes to extract metals:

  • Advantages:
  • They avoid the environmental damage caused by mining and quarrying
  • Disadvantages:
  • Very slow processes
  • They also require electrolysis or displacement reactions to purify the metal which requires a lot of energy and costs a lot

• What is the process of Phytomining:

  1. Plants are planted in the soil which contains the low-grade ore of interest
  2. The plant roots then take up the metal using active transport
  3. Once grown, the plants are harvested, and burned into ashes
  4. This ash is then dissolved in sulfuric acid to form metal sulfate
  5. Extract the metal from the solution using displacement reaction or electrolysis to form the pure metal

• What are the advantages and disadvantages of Phytomining:

  • Advantage:
  • Reduces the need to obtain new ore by mining
  • Conserves the limited supply of high grade ores
  • Disadvantage:
  • It is a very slow process
  • Requires electrolysis or a displacement reaction to purify metal which requires a lot of energy

• What is the process of Bioleaching:

  1. Bacteria is used to flood low-grade ore site and are mixed with the ore
  2. These bacteria able to break down ores to form acidic solution which contain the metal ions
  3. This solution is called a leachate
  4. The metal can be purified by a displacement reaction or electrolysis

• What are the advantages and disadvantages of Bioleaching:

  • Advantage:
  • Reduces the need to obtain new ores by mining
  • Does need high temperatures
  • Conserves limited supply of high grade ores
  • Disadvantage:
  • Very slow process
  • Some toxic chemicals are produced which may damage the environment
  • Requires electrolysis or a displacement reaction to purify metal which requires a lot of energy

Life Cycle Assessment(LCA):

• What is a life cycle assessment:

  • It is an analysis of the overall environmental impact that a product may have throughout its life time
  • It consists of 4 stages:
  • Raw materials
  • Manufacture
  • Usage
  • Disposal

• What does it asses in each stage:

  • Energy use
  • Water usage
  • Transport needed
  • Waste and pollutants produced

Reusing and recycling:

• What are the Advantages of recycling:
  • Economically beneficial to recycle metals as they are hard and costly to extract
  • Environmentally beneficial as less extraction of resources takes place which means less energy is used so less climate change and also less habitats are destroyed for extraction
  • Decreases the amount of waste produced, which means less space is needed for landfill and less energy is used to transport them to land fill
  • It is sustainable as some resources are finite and so less resources are being extracted
• What are the disadvantages of recycling:
  • Collection and transport of material to be recycled requires energy which comes from fossil fuels
  • Materials need to be sorted before they can be recycled which also requires energy and takes time
  • The quality of the product decreases when materials are recycles
  • With some materials it is hard to separate them into individual products and so it requires more energy and time to separate them

Corrosion and Rusting:

• What is the definition of corrosion:

  • The destruction of materials by chemical reactions with substances in the environment through oxidation

• How does oxidation in aluminium work:

  • When aluminium oxidises, the aluminium oxide forms a strong protective layer that covers the aluminium to prevent further corrosion

• What does corrosion affect:

  • It decreases the strength of material
  • It worsens the appearance of the metal

• What is the main example of corrosion:

  • Rusting

• What is rusting:

  • A redox reaction between:
  • iron + water + oxygen → hydrated iron(III) oxide

• When and why does rusting happen faster:

  • It happens in the presence of salty water because sodium chloride in the water catalyses the reaction

Rusting investigation:

• Describe the rusting investigation:
  • Set up 3 test tubes and place an iron nail:
  • 1 test tube is filled with half water and air
  • 1 Test tube is filled with boiled water(to remove any dissolved oxygen) all the way to the top and place oil
  • 1 Test tube with no water, but sodium chloride salt(it acts as a drying agent)at the bottom
  • Leave the apparatus for a few days to give it time to react
• What are the results of the investigation:
  • The first nail rusts because its in contact with both air (which contains oxygen) and water
  • The second nail does not rust because there is no air and so no oxygen
  • The third nail does not rust as it is not in contact with water(calcium chloride absorbs any water molecules present due to moisture)
• What does the investigation show:
  • It shows that both air and water must be present for rusting to occur

Rust prevention:

• What are the 2 methods of rust prevention:

  • Barrier methods/coating
  • Galvanisation(sacrificial protection)

• What are 3 coatings used to prevent rusting:

  • Oil
  • Paint
  • grease
  • electroplating - uses electrolysis to put a thin layer of metal on the object

• Describe the process of electroplating:

  • Uses electrolysis to put a thin layer of metal on the object
  • The Cathode is the iron or steel object
  • The anode is the plating metal
  • the electrolyte contains ions of the plating metal
  • It works by improving corrosion resistance of metal objects

• What is meant by galvanising and how does it work:

  • Coating iron or steel in a thin layer of zinc(using a more reactive metal
  • It works by the zinc layer stopping air and water reaching the iron underneath by reacting with the oxygen in the air to oxidise before the iron does

• What happens if the layer of zinc is scratched:

  • The iron is still protected from rusting because the zinc is more reactive and so the oxygen would rather react with the zinc than the iron and so it doesn’t rust

Alloys as useful materials:

Copper alloys:

• What are 2 copper alloys:

  • Bronze(copper and tin)
  • Brass(Copper and zinc)

• What are the properties and uses of Bronze:

  • It is harder than copper
  • Used in making in statues, ornaments and medals

• What are the properties and uses of Brass:

  • Corrosion resistant
  • Used for low friction ornamental purposes such are plumbing and carpentry

Gold Alloys:

• What is gold most often alloyed with:
  • Silver
  • Copper
  • Zinc
• Why is gold alloyed:
  • Because it is a relatively soft and malleable metal and so it is alloyed to increase strength while keeping its ability to stay shiny
• What are carats:
  • The proportion of gold in the gold alloy is measured in carats.
  • 24 carats is pure gold

Steel Alloys:

• What are steel alloys:
  • Alloys of iron that contain specific amounts of carbon and certain metal elements
• What are the 3 types of steel alloys:
  • High carbon steel
  • Low carbon steel
  • Stainless steel
• What are the elements added to each alloy and the alloy’s properties:
  • High carbon steel: Carbon - Strong, brittle
  • Low carbon steel: Carbon - Softer, more easily shaped
  • Stainless steel: Chromium and nickel - Hard, resistant to rusting

Aluminium Alloys:

• What the properties of aluminium alloys:
  • Magnalium:
  • Low density
  • Stronger than aluminium alone
• What are uses of magnalium:
  • Used in aircraft parts

Ceramics, Polymers and Composites:

Glass ceramics:

• What are the 2 types of glass ceramics:
  • Soda-lime glass
  • Borosilicate
• How is soda lime glass made:
  • Melting a mixture of sand(silicon oxide) Sodium carbonate, Limestone
  • Allow the molten liquid to cool and solidify
• How is borosilicate glass made:
  • Heating silicon oxide with boron trioxide.
  • It has a much higher melting point
• Why are glass ceramics good:
  • Strong, durable and glass insulates against heat

Clay Ceramics:

• How are they made:
  • They are made by shaping wet clay and then heating it to a high temperature in a furnace, which causes crystals to form and join together, causing it to dry and harden
• Why and what are they coated with:
  • They are often coated with a glaze, which hardens on heating to form a hard, smooth, opaque and waterproof layer

Polymers:

• What are the 2 types of polymers:

  • Low density poly(ethene) - LDPE
  • High density poly(ethene) - HDPE

• How is LDPE produced:

  • High pressure and moderate temperature, which produces flexible LDPE

• How is HDPE produced:

  • Lower temperatures and pressures and with the use of a catalyst. Which creates more rigid, solid structure

• What are the properties and uses of types of polymers:

  • LDPE: Flexible, uncreative, can be made into film, Uses: Most carrier bags, bubble wrap
  • HDPE: Strong, flexible, resists shattering resists chemical attack, Uses: plastic bottles, pipes, buckets

• How are LDPE and HDPE arranged:

  • LDPE: The polymer chains are randomly arranged(branched)
  • HDPE: The polymer chains are less branched and so they molecules line up much more closely

Plastics:

• What are the 2 types of plastics:

  • Thermosoftening
  • Thermosetting

• What are Thermosoftening plastics and how are they structured:

  • They melt when they are heated
  • They have no cross links between polymer molecules (no covalent bonds between molecules)

• What can Thermosoftening plastics do and why:

  • The polymers chains can slide over each other when heated,
  • which allows them to melt and makes them soft, which means they can be recycled
  • because there are no cross links between the polymer molecules

• What are thermosetting plastics and how are they structured:

  • Plastics that do no melt when heated
  • This means that they tend to char and burn when heated
  • They have cross links between polymer chains

• What are the uses of thermosetting plastics:

  • They are used to make electrical plugs, which must not melt

Composite materials:

• What is a composite material:

  • Consists of 2 or more materials with different properties, to improve the original material’s properties

• What are most composites made out of:

  • Reinforcement
  • The matrix - which binds the reinforcement together

• What are 4 examples of composites:

  • Reinforced Concrete
  • Fibre glass
  • Carbon fibre reinforced polymer
  • Chipboard

• What properties does reinforced concrete have and why:

  • Very strong but slightly flexible
  • Because it has great tensile and compression strength

• What properties does Fibre glass and carbon fibre reinforced polymer(CFRP) have and why:

  • They are strong, stiff and lightweight
  • They are strong because of their tensile strength
  • They are stiff because resin is stiff, and it binds the fibres together
  • They are light weight because fibres have a low density

• What is wood made of:

  • It is a natural composite material.
  • The reinforcements of cellulose fibres bonded together by a matrix of lignin.

• How is Chipboard aligned:

  • They are aligned alongside each other, so wood is stronger one way than the other.
  • Chipboard contains randomly arranged wood chips bonded together by a glue, so it is strong in all directions

The Haber process:

• What are the stages of the Haber process:
  • Stage1: H2 from natural gas and N2 from the air gases are pumped into the compressor through pipes
  • Stage 2: The gases are compressed to about 200 atmospheres inside the compressor
  • Stage 3: The pressurised gases are heated to 450C and passed through a tank containing an iron catalyst. Some hydrogen and nitrogen react to form ammonia in a reversible reaction:
  • N2 + 3H2
  • Stage 4: Unreacted H2 and N2 and product ammonia pass into a cooling tank. The ammonia is liquified and removed to pressurised storage vessels
  • Stage 5: The unreacted H2 and N2 are recycled back into the system

NPK fertilisers:

• What do they contain:

  • Nitrogen
  • Potassium
  • Phosphorus

• Why are NPK fertilisers used:

  • To provide nutrients, which are not soluble naturally, to the soil for the root hair cells in the roots to absorb them

• Why are these 3 essential nutrients needed:

  • Nitrate ions are needed for the production amino acids for healthy leaves
  • Potassium ions promote growth, healthy fruit and flowers
  • Phosphorus ions promote healthy roots

• What are the sources of each minerals:

  • soluble nitrogen: ammonium ions, nitrate ions
  • soluble phosphorus: phosphate ions
  • soluble potassium: all potassium compounds dissolve in water

• What are 4 types fertilisers:

  • Ammonium nitrate
  • Ammonium sulfate
  • Ammonium Phosphate
  • Potassium nitrate

Ammonium sulfate:

• What is ammonium sulfate and how is it produced:

  • It is a sulfate used as a fertiliser
  • It is produced by reacting ammonia and sulfuric acid

• Describe the process of producing ammonium sulfate in the chemical industry:

  • Stage 1: Nitrogen is extracted from the air, hydrogen is extracted from either water or natural gas, Sulfur trioxide is produced by reacting the oxygen in the air with sulfur
  • Stage 2: Ammonia is then produced from nitrogen and hydrogen during the Haber process and sulfuric acid is produced from sulfur trioxide and water reacting
  • Stage 3: Ammonium sulfate is produced from a reaction between Ammonia and Sulfuric acid under 60C

• Describe the process of producing ammonium sulfate in the laboratory:

  • Titrating ammonia solution and sulfuric acid
  1. 25cm^3 ammonia solution is measure using a pipette and poured into a clonical flask, over a white tile
  2. 2 Drop of methyl orange indicator are added which will turn yellow in the alkaline ammonia solution
  3. A burette is filled with dilute sulfuric acid using a funnel until it reaches 0cm^3 while making sure the tap is closed
  4. Slowly add the sulfuric acid onto the ammonia solution while swirling the flask, in order to mix it properly, keep adding sulfuric acid until the solution turns orange
  5. The volume of sulfuric acid which has been added is recorded, and the solution is thrown away
  6. The experiment is then repeated without the indicator, but with the same volumes of ammonia and sulfuric acid
  7. The ammonium sulfate solution is then crystallised using a water bath and an evaporating basin

Phosphate rock:

• What 3 acids can phosphate rock react with:

  • Nitric acid
  • Sulfuric acid
  • Phosphoric acid

• What does the reaction with nitric acid produce:

  • Calcium nitrate and Phosphoric acid
  • Phosphoric acid is then neutralised with ammonia to make ammonium phosphate

• What does the reaction with Sulfuric acid produce:

  • Single superphosphate
  • Which is a mixture of calcium sulphate and calcium phosphate

• What does the reaction with Phosphoric acid produce:

  • Triple superphosphate
  • Which is only calcium phosphate