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Chemistry > Topic 4 – Extracting metals and equilibria > Flashcards

Topic 4 – Extracting metals and equilibria Flashcards

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1
Q

oxidation

A
  • gain of oxygen
  • loss of electrons
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2
Q

reduction

A
  • loss of oxygen
  • gain of electrons
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3
Q

redox reaction

A

when both reduction and oxidation happen simultaneously.
One compound is reduced and the other is oxidised

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4
Q

displacement reaction

A

When a more reactive metal displaces a less reactive metal from its compound

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5
Q

what happens in a displacement reaction

A
  • more reactive metal is oxidised : losing electrons. It becomes a cation
  • less reactive metal ions are reduced : gaining electrons. it becomes an atom
  • the positive metal ions bond with the negative ions to from the new compound, leaving the less reactive metal on its own
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6
Q

OIL RIG ( electrons )

A

Oxidation Is Lost
Reduction Is Gained

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7
Q

metals at top of reactivity series

A
  • lose their electrons to form cations more easily
  • gain oxygen more easily
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8
Q

metal + acid -> ?

A

salt + hydrogen

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9
Q

metals at bottom of reactivity series

A
  • lose their electrons to form cations less easily
  • gain oxygen less easily
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10
Q

how to test reactivity of metals

A
  • see how quickly hydrogen is produced when you react metal with acid by attaching a gas syringe
  • see how loud the squeaky pop sound is when you bring a lit splint near it
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11
Q

metal + water ->

A

metal hydroxide + hydrogen

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12
Q

reactions between metal and metal salt solutions

A
  • see how many times the metal displaces another metal from its solution
  • the metal with the most times is the most reactive
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13
Q

how do we extract metals such as gold

A

they are found in the crust as uncombined elements

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14
Q

metal ore

A

a rock that contains enough metal to make it profitable to extract metal from it

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15
Q

how are metals below carbon in reactivity series extracted from its ore? ( REDOX )

A
  • reduced in a reaction with carbon
  • because the carbon is more reactive it displaces the metal from its compound
  • carbon is oxidised and metal reduced
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16
Q

how are metals above carbon in reactivity series extracted from its ore?

A

electrolysis

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17
Q

electrolysis of aluminium ( part 1 )

A
  • purify bauxite ( ore ) and extract the aluminium oxide
  • mix it with cryolite which lowers boiling point - cheaper, saves energy
  • melt it to form molten Al2O3 which is our electrolyte
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18
Q

electrolysis of aluminium ( part 2 )

A
  • put molten Al2O3 in beaker and put 2 graphite electrodes in it.
  • positive electrode which attracts anions + negative electrode which attracts cations
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19
Q

electrolysis of aluminium ( part 3 )

A
  • the positive electrode attracts the negative oxygen ions and they react with carbon to form CO2
  • the negative electrode attracts the positive Al3+ ions and they gain 3 electrons to form aluminium atoms and sink to bottom of beaker
20
Q

disadvantages of electrolysis

A
  • positive electrode must be replaced regularly
  • vast amount of electricity required
  • energy intensive
21
Q

why do we use alternative methods of extraction?

A
  • supply of some metal rich ores is running out
  • this means we have to extract metals from low grade ores
  • traditional methods are expensive and energy intensive
22
Q

bioleaching

A

-bacteria mixed with low grade ore
- produces leachate which is soluble metal ore and contains higher concentration of metal ions
- these metal ions can be extracted through traditional methods

23
Q

phytomining / phytoextraction

A
  • plants grown on land containing metal compound
  • metal compounds build up in leaves - plant harvested and burned in furnace
  • ash contains high concentration of metal ions
24
Q

advantages of alternative methods

A
  • economical/ cheap
  • much smaller environmental impact
  • require less energy/ electricity
  • don’t involve digging or transporting huge amounts of metal ores
25
Q

disadvantages of alternative methods

A
  • slower process
  • metals in ground could harm plants in very high concentrations
26
Q

sustainable development

A
  • meets the needs of current generations without damaging lives of future generations
27
Q

advantages of recycling -

A
  • conserving energy and resources
  • environmental benefits
  • economic benefits
28
Q

conserving energy and resources

A
  • you use up less non renewables
  • avoid burning fossil fuels which is very energy intensive
29
Q

environmental benefits

A
  • less mines dug
  • ## less waste in landfill
30
Q

economic benefits

A
  • recycling metals can save money as metals are expensive to extract
  • creates new jobs and improves economy
31
Q

what 2 factors make metals more important to recycle

A
  • more expensive to manufacture
  • low quantity in earth’s crust
32
Q

4 stages of Life cycle assessment
( R MUP )

A
  • raw materials
  • manufacturing and packaging
  • usage
  • disposal
33
Q

alloy

A

mixture of 2 or more materials where at least 1 is a metal

34
Q

why are pure metals more malleable? ( part 1 )

A
  • regular arrangement of identical ions
  • layers of ions can easily slide over each other, bending the metal
35
Q

why are alloys stronger? ( part 2 )

A
  • different elements have different sized atoms
  • the smaller atoms will disrupt the regular arrangement of the bigger atoms
  • this makes it MORE difficult for layers to slide over each other
36
Q

steels

A
  • iron that is alloyed with other elements
  • makes iron stronger and less likely to rust
37
Q

corrosion

A

when metals break down in the presence of oxygen and water to form their metal oxide

38
Q

rusting

A

corrosion of iron

39
Q

water, no oxygen

A
  • nail is placed in water and a layer oil oil added on top to stop oxygen from entering
  • no rusting
40
Q

oxygen, no water

A
  • nail placed in test tube and calcium chloride absorbs all water
  • no rusting
41
Q

water and oxygen

A

rusting

42
Q

why is preventing corrosion so important?

A

structures such as metal bridges corrode over time and start to break down which makes it dangerous to walk on

43
Q

creating a barrier

A

painting it
oiling or greasing
electroplating

44
Q

sacrificial protection

A

placing more reactive metal with the metal
oxygen and water will react with the reactive metal instead

45
Q
A

Chemistry (13 decks)

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