1.3 Metals and their extraction

Question 1

ToF, Gold has to be extracted chemically

Answer 1

F

Question 2

The more reactive the metal…

Answer 2

…the more stable its compund

Question 3

the more stable a metal’s compound…

Answer 3

…the more difficult it is to extract the metal from the compund

Question 4

example of displacement reaction

Answer 4

iron oxide + aluminium -> aluminium oxide + iron

Question 5

what are oxidation reactions?

Answer 5

reactions in which oxygen is gained or electrons are lost

Question 6

what are reduction reactions?

Answer 6

reactions in which oxygen is lost or electrons are gained

Question 7

What is a REDOX reaction?

Answer 7

where reduction and oxidation take place at the same time

Question 8

what materials are used to make iron in a blast furnace?

Answer 8

iron oxide, coke, limestone and air

Question 9

what is iron oxide made up of?

Answer 9

iron + impurities

Question 10

function of limestone in extraction of iron?

Answer 10

to remove impurities such as silicon oxide (sand) to form slag whioch then floats on top of the molten iron

Question 11

function of coke in extraction of iron?

Answer 11

it is used as fuel to produce carbon monoxide for the reduction of iron oxide

Question 12

function of hot air in extraction of iron?

Answer 12

allows the carbon (coke) to burn

Question 13

How is iron extracted, step by step?

Answer 13

• coke and oxygen combist to form CO₂.
• CO₂ binds with more coke to form carbon monoxide.
• REDOX reaction between iron oxide and CO to form iron and CO₂ -> iron oxide is reduced to iron, and carbon monoxide is oxidised to CO₂.
• as this happens. the CaCO₃(limestone) thermally decomposes to form CaO and CO₂.
• the CaO binds (neutralisation) with SiO₂ (sand) to form CaSio₂ (slag) and floats to the top of the molten iron
• iron is displaced with carbon to form pig iron, which can be turned to steel when excess carbon is removed

Question 14

explain the electrolysis of lead bromide, step by step

Answer 14

1. The lead bromide is heated so the Pb2+ ions and br- ions are free to move around
2. An electrical current is passed through the molten lead bromide (electrolyte)
3. the Pb2+ ions are attracted to the negative cathode whilst the Br- ions are attracted to the positive anode.
4. Two Br- ions get rid of one of their electrons each to become an atom (2Br- - 2e- = Br₂), and these 2 electrons are gained by the Pb2+ ions to become an atom (Pb2+ + 2e- = Pb)
5. This then splits the lead bromide back into elements [PbBr₂ = Pb + Br₂]

Question 15

explain the electrolysis of aluminium oxide, step by step

Answer 15

• before the current is switched on, the aluminium oxide has to be molten to conduct electricity (become an electrolyte), which takes enormous amounts of energy, however this process can be catalysed by the use of cryolite as it can help lowwr its melting point
• once the electrical current is switched on, the Al3+ irons are attracted to the negative cathode and the O2- ions are attracted to the posisive anode.
• ## 6 O2- ions get rid of two of their electrons each to become an atom (3O2- - 6e- = 3O₂), and these 6 electrons are then gained by two Al3+ ions to become atoms (2Al3+ + 6e- = 2Al)