C6.1 Flashcards

1
Q

What is an ore?

A
  • A rock or mineral containing enough metal to make it economical to extract the metal
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2
Q

What are 4 ways metals can be extracted from their compounds?

A
  • Reduction
  • Electrolysis
  • Biological methods
  • Displacement reactions
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3
Q

How is iron extracted from its compound?

A
  • Iron ore is heated with carbon in a blast furnace
  • Iron (III) oxide is reduced to molten iron
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4
Q

How is aluminium extracted?

A
  • Heating aluminium oxide (Al2O3) until it reaches the liquid state would be very expensive, so it is dissolved in molten cryolite, which reduces its melting point, as it itself has a much lower melting point than aluminium
  • It is electrolysed in a cell encased with steel
  • Its electrodes are made of graphite
  • The sides of the cell are the cathode, and graphite blocks at the top of the cell are the anodes
  • Aluminium is produced at the cathode
  • Oxygen is produced at the anodes, and reacts with them to produce carbon dioxide, so they need to be replaced frequently
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5
Q

What is bioleaching?

A
  • Bacteria break down metal ores and produce an acidic solution containing metal ions
  • This solution is called the leachate
  • The leachate can then be processed to produce the metal
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6
Q

What is phytoextraction?

A
  • A crop is planted in soil containing a low-grade ore
  • The plants absorb the metal ions through their roots
  • They are harvested and burnt
  • The ash has a high concentration of metal
  • It is processed to produce the metal
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7
Q

Why are bioleaching and phytoextraction used, and what is their disadvantage?

A
  • To extract metal from low-grade ores
  • They are cheaper than traditional mining and processing
  • They have a much smaller impact on the environment than mining
  • Both processes are slow
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8
Q

What is the Contact Process? List its 3 stages.

A
  • Process to make sulfuric acid
  • Sulfur burns in the air to make sulfur dioxide:
    S + O2 -> SO2
  • 2SO2 + O2 -> 2SO3
  • H2O + SO3 -> H2SO4
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9
Q

Which stage of the process is reversible? state the conditions chosen for it, and why they’re chosen.

A
  • Stage 2
  • A pressure of 2atm, as the position of equilibrium is already far to the right
  • A temperature of 450°C as although the forward reaction is exothermic, the rate of reaction needs to be reasonable
  • Vanadium (V) oxide catalyst (V2O5)
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10
Q

What is the Haber process?

A
  • N2 + 3H2 -> 2NH3 (reversible)
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11
Q

What are the conditions used in the Haber process, and why were they chosen?

A
  • 200 atm, which is a compromise as a higher pressure should increase the rate of reaction, but high pressures are expensive and dangerous to maintain
  • 450°C as although the forward reaction is exothermic, the rate of reaction needs to be reasonable
  • Iron catalyst
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12
Q

What else is done to make the production of ammonia efficient?

A
  • Unused hydrogen and nitrogen are recycled
  • The gases are cooled so ammonia condenses and leaves the reaction vessel
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13
Q

What are factors to consider when choosing an industrial process?

A
  • Cost of raw materials
  • Availability of raw materials
  • Energy costs
  • Rate
  • Equilibrium position
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14
Q

What 3 of the essential elements needed by plants, and what does a lack of them cause?

A
  • Nitrogen
  • Phosphorus
  • Potassium
  • Poor growth and discoloured leaves
  • A reduction in the quantity and yield of food
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15
Q

What are fertilisers?

A
  • Substances that replace the elements used by plants
  • They can only be used by plants if they’re in a water-soluble form
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16
Q

What are 2 fertilisers used in agriculture, and what are the raw materials some of them are they made from?

A
  • Ammonium nitrate
  • Ammonium sulfate
  • Nitrogen: air
  • Hydrogen: natural gas and water
  • Sulfur
17
Q

How is potassium sulfate made?

A
  • Titration using potassium hydroxide, sulfuric acid and phenolphthalein
  • When the titration has reached its end point, activated charcoal is added
  • This attracts the phenolphthalein so they can be filtered out together
18
Q

How is ammonium sulfate made?

A
  • Titration using ammonia solution, sulfuric acid and methyl orange (red in acids and yellow when neutral)
  • The amount of acid needed to reach the end point should be recorded so the process can be repeated without any indicator
19
Q

What is a batch process, and what is a continuous process?

A
  • Batch processes make products in limited amounts at different times
  • Continuous processes make products in large amounts all the time, so tend to be used in industry
20
Q

How are continuous processes different to batch processes?

A
  • Their rate of production is higher
  • They need fewer workers
  • Shut-down periods are rare
  • It is easy to automate the process
  • The equipment needed is more expensive
21
Q

What is an alloy?

A
  • A mixture of 2 or more elements, at least one of which is a metal
22
Q

What is steel made of, some of its properties, and some uses of it?

A
  • Mainly iron, and some carbon
  • It is harder and stronger than iron, but less likely to rust than it
  • Buildings, bridges and cars
23
Q

What is duralumin made of, some of its properties, and a use of it?

A
  • Aluminium and copper
  • Has a very low density, but is stronger than aluminium
  • Aircraft parts
24
Q

What is solder made of, some of its properties, and a use of it?

A
  • Tin and lead
  • It gradually solidifies as it cools down, and is a good conductor of electricity
  • Joining components in electrical circuits as it can be worked easily
25
Q

What is brass made of, one of its properties, and some uses of it?

A
  • Copper and zinc
  • It is harder than copper and zinc
  • Musical instruments
26
Q

What is bronze made of, some of its properties, and some uses of it?

A
  • Copper and tin
  • Harder and stronger than both metals, and more resistant to corrosion than both of them
  • Bells and sculpture
27
Q

What is corrosion?

A
  • The reaction of a metal with substances in its surroundings, such as air and water
28
Q

Give examples of corrosion, and what they’re caused by.

A
  • Silver: hydrogen sulfide, oxygen and water
  • Iron and steel: oxygen and water
  • Metals like gold and platinum do not corrode at all
29
Q

Describe the corrosion of iron.

A
  • When iron and steel corrode it us known as rusting
  • Iron + oxygen + water -> hydrated iron (III) oxide
  • Hydrated iron oxide is orange-brown rust, which flakes off of the object, until more metal is exposed underneath, and this can continue until the entire object corrodes away
30
Q

How can rusting be reduced?

A

Making a barrier between the iron and oxygen/ water.
- Painting
- Coating with oil, grease or plastic
- Plating with tin
- Galvanising

31
Q

What is the problem with most methods of protecting iron from rusting?

A
  • If the protective barrier is damaged, the iron is exposed to air and water
  • If a less reactive metal than iron, such as tin, is used, it rusts even faster than normal when it becomes exposed to air and water
32
Q

What is sacrificial protection? Give an example.

A
  • Coating a metal with a more reactive metal, as the layer of metal acting as protection will be oxidised more easily, even if the metal underneath becomes exposed
  • Galvanising is when iron is coated with a layer of zinc
33
Q

What are ceramics, and what are some of their common properties?

A
  • Hard, non-metallic materials
  • Include: brick, china, porcelain and glass
  • High melting points, hard and stiff yet brittle, poor conductors of electricity and heat
34
Q

What are composite materials? Give 2 examples.

A
  • Two or more materials combined together that have different properties
  • One material (the reinforcement) is embedded in another material (the matrix/ binder)
  • Fibreglass is made from fibres of glass in a polymer matrix
  • It has a low density like the polymer, but is strong like glass
  • Concrete is made from aggregate in cement, and has a high compressive strength
35
Q

What is a life-cycle assessment, and what should it include?

A
  • ‘Cradle to grave’ analysis of the impact of making, using and disposing of a manufactured product
  • Use of raw materials and energy for production
  • The transport of the product
  • The product’s lifespan and if any of it can be recycled
  • The disposal of the product, and how easily any of it can decompose
36
Q

Why is recycling important?

A
  • It conserves raw materials and energy
  • Reduces the release of of harmful substances in the environment
  • Reduces waste
37
Q

Which aspects of recycling should be considered when deciding to recycle a material?

A
  • How easy sorting it is
  • If making it from raw materials requires less energy than recycling it
  • If recycling or disposal is cheaper
  • How many times it’s been recycled before, as this reduces the quality of the material
  • The amount and type of by-products released
38
Q

How are some materials recycled?

A
  • Metals, glass and polymers are heated and moulded again
  • Paper is mixed with water, cleaned, rolled and heated