Topic 4 – Extracting metals and equilibria

Question 1

oxidation

Answer 1

• gain of oxygen
• loss of electrons

Question 2

reduction

Answer 2

• loss of oxygen
• gain of electrons

Question 3

redox reaction

Answer 3

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

Question 4

displacement reaction

Answer 4

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

Question 5

what happens in a displacement reaction

Answer 5

• 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

Question 6

OIL RIG ( electrons )

Answer 6

Oxidation Is Lost
Reduction Is Gained

Question 7

metals at top of reactivity series

Answer 7

• lose their electrons to form cations more easily
• gain oxygen more easily

Question 8

metal + acid -> ?

Answer 8

salt + hydrogen

Question 9

metals at bottom of reactivity series

Answer 9

• lose their electrons to form cations less easily
• gain oxygen less easily

Question 10

how to test reactivity of metals

Answer 10

• 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

Question 11

metal + water ->

Answer 11

metal hydroxide + hydrogen

Question 12

reactions between metal and metal salt solutions

Answer 12

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

Question 13

how do we extract metals such as gold

Answer 13

they are found in the crust as uncombined elements

Question 14

metal ore

Answer 14

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

Question 15

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

Answer 15

• 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

Question 16

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

Answer 16

electrolysis

Question 17

electrolysis of aluminium ( part 1 )

Answer 17

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

Question 18

electrolysis of aluminium ( part 2 )

Answer 18

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

Question 19

electrolysis of aluminium ( part 3 )

Answer 19

• 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

Question 20

disadvantages of electrolysis

Answer 20

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

Question 21

why do we use alternative methods of extraction?

Answer 21

• 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

Question 22

bioleaching

Answer 22

-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

Question 23

phytomining / phytoextraction

Answer 23

• 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

Question 24

advantages of alternative methods

Answer 24

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

Question 25

disadvantages of alternative methods

Answer 25

- slower process - metals in ground could harm plants in very high concentrations

Question 26

sustainable development

Answer 26

- meets the needs of current generations without damaging lives of future generations

Question 27

advantages of recycling -

Answer 27

- conserving energy and resources - environmental benefits - economic benefits

Question 28

conserving energy and resources

Answer 28

- you use up less non renewables - avoid burning fossil fuels which is very energy intensive

Question 29

environmental benefits

Answer 29

- less mines dug - less waste in landfill -

Question 30

economic benefits

Answer 30

- recycling metals can save money as metals are expensive to extract - creates new jobs and improves economy

Question 31

what 2 factors make metals more important to recycle

Answer 31

- more expensive to manufacture - low quantity in earth's crust

Question 32

4 stages of Life cycle assessment ( R MUP )

Answer 32

- raw materials - manufacturing and packaging - usage - disposal

Question 33

alloy

Answer 33

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

Question 34

why are pure metals more malleable? ( part 1 )

Answer 34

- regular arrangement of identical ions - layers of ions can easily slide over each other, bending the metal

Question 35

why are alloys stronger? ( part 2 )

Answer 35

- 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

Question 36

steels

Answer 36

- iron that is alloyed with other elements - makes iron stronger and less likely to rust

Question 37

corrosion

Answer 37

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

Question 38

rusting

Answer 38

corrosion of iron

Question 39

water, no oxygen

Answer 39

- nail is placed in water and a layer oil oil added on top to stop oxygen from entering - no rusting

Question 40

oxygen, no water

Answer 40

- nail placed in test tube and calcium chloride absorbs all water - no rusting

Question 41

water and oxygen

Answer 41

rusting

Question 42

why is preventing corrosion so important?

Answer 42

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

Question 43

creating a barrier

Answer 43

painting it oiling or greasing electroplating

Question 44

sacrificial protection

Answer 44

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