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Chemistry C1 > Metals and their uses > Flashcards

Metals and their uses Flashcards

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1
Q

Where do metals come from?

A

The Earth’s crust (combined with other chemical elements like oxygen)

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2
Q

What is an ore?

A

A rock where there is enough of the metal or metal compound to make it worth extracting

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3
Q

Why are silver and gold found as metals (pure) in the ground?

A

They are very unreactive and in their native state

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4
Q

What does native mean? (metals)

A

A metal which is found by itself, rather than in a compound- called a nugget

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5
Q

What is reduction?

A

When a metal is purified and we remove the oxygen from the compound

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6
Q

What is the reduction equation?

A

Metal oxide + carbon –> metal + carbon dioxide (If carbon is used to displace the oxygen)

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7
Q

Name the reactivity series from series from most reactive to least reactive…

A 
Potassium
Sodium
Calcium
Magnesium
Aluminium
(CARBON)
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
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8
Q

How are metals lower in the reactivity series than carbon extracted?

A

Reduction by carbon

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9
Q

What is an example of reduction by carbon?

A

E.g. iron oxide is reduced in a blast furnace to make iron

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10
Q

How are metals higher in the reactivity series than carbon extracted?

A

Electrolysis- this is because carbon can only take oxygen away from metals from metals which are less reactive than carbon itself

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11
Q

What are the problems of electrolysis?

A
  • Expensive
  • More energy required
  • Latter may have been made from burning fossil fuels causing pollution
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12
Q

Give an example of a metal which requires electrolysis to extracted…

A

(Anything above carbon in the reactivity series)
Aluminium:
A high temperature is needed to melt aluminium oxide so that aluminium can be extracted- this requires a lot of energy making it expensive

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13
Q

What is smelting?

A

When a metal is extracted from its ore by the process of heating (in a furnace)

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14
Q

How is copper purified and what are the benefits of this?

A

Electrolysis:
Copper can easily be extracted by reduction with carbon but it comes out as impure- this means it cannot conduct electricity well so electrolysis is used to purify it
Benefit: very pure copper is a very good conductor even if electrolysis is expensive

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15
Q

What is electrolysis and what does the process involve?

A

Electrolysis is the breaking down of a substance using electricity

  • requires a liquid to conduct electricity- the electrolyte
  • electrolytes are often in metal salt solutions made from the ore or molten metal oxides
  • the electrolyte has free ions- these conduct electricity and allow the whole thing to work
  • electrons are taken away by the positive anode and given away by the negative cathode- as ions gain or lose electrons they become atoms or molecules and are released
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16
Q

How is electrolysis used to get copper?

A
  • Electrons are pulled off copper atoms at the anode (positive rod), causing them to go into solution as Cu2+ ions
  • Cu2+ ions near the cathode (negative rod) gain electrons and are turned back into copper atoms
  • The impurities are dropped at the anode as sludge whilst the pure copper atoms bond to the cathode
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17
Q

Is pure iron useful?

A

No- pure iron is too soft to be useful and is therefore mixed with other elements to make alloys

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18
Q

What is pig iron?

A

Iron which has not had all of the carbon and impurities removed

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19
Q

What is the name for an iron alloy?

A

Steel

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20
Q

What is the name of iron which has been alloyed with a little carbon?

A

Carbon steel

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21
Q

What is the difference between high-alloy and low-alloy steels?

A

High-alloy steels are more expensive, containing a higher percentage of other metals- up to 12-15% from 1-5%

22
Q

Why are surgical instruments made from steel? (What element has been added to the iron?)

A

Steel containing chromium and nickel are used because they have a greater resistance to corrosion and won’t rust

23
Q 
Name the properties of carbon steel...
(- % iron to other element
- other element
- cost
- uses)
A
  • Iron= 98.5-99.97% Other element= 1.5-0.03%
  • carbon
  • cheapest steel to make
  • bodies of cars, knives, machinery, ships, containers, structural steel for buildings
24
Q 
Name the properties of low-alloy steel...
(- % iron to other element
- other element
- cost
- uses)
A
  • Iron= 95-99% Other element= 1-5%
  • nickel, chromium, manganese, vanadium, titanium, tungsten
  • more expensive than carbon steel
  • long span bridges, bicycle chains, military armour plating
25
Q 
Name the properties of high-alloy steel...
(- % iron to other element
- other element
- cost
- uses)
A
  • Iron= 85-88% Other element= 12-15%
  • chromium, nickel
  • even more expensive than low-alloy steel
  • cooking utensils, cutlery, surgical instruments
26
Q

What are the properties of aluminium?

A
  • Silver, shiny with surprisingly low density for a metal
  • Good conductor of heat and electricity
  • Malleable (easily shaped) so can be drawn into wires easily
  • Relatively reactive but does not corrode easily (reacts immediately with oxygen to form tough layer of aluminium oxide)
  • Not particularly strong but can use it to form harder and stronger alloys
27
Q

What are the uses of aluminium?

A
  • Cans
  • Cooking foil
  • Saucepans
  • High-voltage electricity cables
  • Aeroplanes
  • Space vehicles
28
Q

How is aluminium extracted?

A
  • The aluminium ore is mined containing extra impurities
  • A high temperature is needed to melt aluminium oxide so that aluminium can be extracted- this requires a lot of energy making it expensive
  • An electric current is passed through aluminium oxide at high temperatures to break it down
29
Q

What are the properties of titanium?

A
  • Silver-white metal
  • Very strong
  • Very resistant to corrosion
  • Like aluminium it forms a protective oxide layer
  • Denser than aluminium but less dense than most transition metals
  • High melting point at 1660 degrees celsius
30
Q

What are the uses of titanium?

A
  • Bodies of high-performance aircraft and racing bikes (due to low density and strength)
  • Nuclear reactors- pipes (due to high melting point)
  • Replacement hip joints (due to resistance to corrosion)
31
Q

How is titanium extracted?

A
  • Can be displaced by carbon (being lower in the reactivity series) however they react together, making the titanium brittle
  • A more reactive metal such as sodium or magnesium is used to displace it
  • The ore must be processed by separating the titanium oxide and converting it to titanium chloride which is distilled and purified
  • The titanium is then displaced by the sodium (or magnesium)- this process is very long and expensive
32
Q

Why should metals be recycled?

A
  • Lots of money is involved in extracting and using them
  • It takes a lot of time to produce the metals
  • There is a lot of energy involved which involves the burning of fossil fuels a lot of the time- this causes pollution
  • No point in wasting already usable material
  • Extra bi-products are given off in the metal’s production so this should be limited as much as possible
33
Q

Why is copper in high demand?

A
  • Useful properties
  • Good for electrical wiring and plumbing
  • Good conductor of heat and electricity
  • Unreactive with water
34
Q

Give examples of new methods used to extract copper from low-grade ores…

A
  • Bioleaching

- Phytomining

35
Q

What are the pros and cons of mining ores?

A

Pros:

  • useful products can be made
  • Provides jobs to local people
  • Brings money to area
  • Services such as transport and health can be improved (with influx of money)

Cons:

  • Noise pollution
  • Scars landscape
  • Loss of natural habitats
  • Can be dangerous (especially deep, old, abandoned mine shafts)
36
Q

What is the process of bioleaching?

A
  • Uses bacteria to separate copper from copper sulfide
  • Bacteria gain energy from the bond between copper and sulfur, separating the copper out from the ore in the process
  • The leachate (solution produced from the process) contains copper which can be extracted e.g. by filtering, displacement (using scrap iron), electrolysis
37
Q

What is the process of phytomining?

A
  • This involves growing plants in soils which contain copper
  • The plants can’t use or get rid of the copper so they just absorb it and it builds up in the leaves
  • The plants can then be harvested, dried and burned in a furnace
  • The copper can be collected from the ash
38
Q

What are the benefits and drawbacks of the new methods bioleaching and phytomining?

A

Benefits:
- Smaller impact on environment than traditional methods
- Much cheaper
- Bioleaching- 20% of the worlds copper is currently being extracted by this method
Drawbacks:
- Bioleaching- for some metals including copper it is not always economically feasible even with its low cost
- Not very fast processes
- Phytomining- burning releases carbon dioxide, a greenhouse gas, into the environment which increases global warming

39
Q

What is the equation for smelting copper and what are its drawbacks?

A

Copper(+)sulfide + oxygen –> copper + sulfur dioxide

  • Uses lots of energy
  • Expensive
  • Sulfur dioxide produces acid rain
40
Q

Other than electrolysis, how else can copper be extracted from a solution?

A

Displacement

Scrap iron displaces copper which can then be filtered and collected

41
Q

What are the properties of alloys? (9)

A
  • Malleable
  • Ductile
  • Sonorous
  • Conduct heat
  • Conduct electricity
  • Hard
  • Strong
  • High melting and boiling point
  • Shiny
42
Q

What are the properties and uses of aluminium? (simple)

A
  • Cheap, light, conductor

- Electrical cables

43
Q

What are the properties and uses of tungsten?

A
  • Gets hot without melting

- Lamp filaments

44
Q

What are the properties and uses of iron and steel (alloy)? (simple)

A
  • Strong and cheap

- Bridges, boats

45
Q

What are the properties and uses of silver?

A
  • Soft, easy to shape

- Ring making processes

46
Q

What are the properties and uses of mild steel?

A
  • Stretched and shaped easily

- Car making, car parts

47
Q

What are the properties and uses of steel rods (alloy)?

A
  • Makes concrete stronger

- Used to reinforce concrete blocks

48
Q

What are the properties and uses of mordand steel?

A
  • Makes it more resistant to wear

- Gear teeth, cut metal

49
Q

What are the properties and uses of aluminium alloy?

A
  • Stronger, need less of it

- Used in aircraft

50
Q

What are the properties and uses of silver alloy, nickel and copper?

A
  • Easy to shape and cheaper

- Coins (silver coins e.g. 50p)

51
Q

What metals can be displaced?

A

Those lower in the reactivity series than carbon

52
Q

Why is pure iron more “bendy” than iron alloys?

A

The regular arrangement of identical atoms means that the layers can slide over each other, making it soft and easily shaped- iron alloys have different sized atoms making it more irregular as an arrangement and harder

Chemistry C1 (7 decks)

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