Chemistry In Society (a)

Question 1

Occur as elements in their ores

Occur as compounds

Answer 1

Only the most unreactive metals such as gold and silver

Most (from which the metals have to be extracted)

Question 2

Ore

Answer 2

A rock that contains enough metal to make it worth mining

Question 3

The more reactive the metal…

Answer 3

The more difficult and expensive it is to extract

Question 4

Extraction of aluminium diagram

Answer 4

Tapping hole
Indulation
Neg electrode- lining 
Electrolyte 
Positive electrode- in many strands

Question 5

Extraction of aluminium electrodes made of…

Answer 5

Carbon

Question 6

Extraction of aluminium electrolyte

Answer 6

A solution of aluminium oxide dissolved in molten cryolite

Question 7

Main ore of aluminium

Answer 7

Bauxite

Question 8

Why is the +ve electrode for extraction of aluminium in a chain

Answer 8

To increase surface area for the electrolyte ti reach the electrodes

Question 9

Why is aluminium oxide dissolved in molten cryolite?

Answer 9

Aluminium oxide has a v high mp and it is dissolved in molten cryolite to make the electrolyte
Mixture has much lower mp and is also a better conductor of electricity than molten aluminium oxide

Question 10

What happens first to the main ore of aluminium?

Answer 10

The bauxite is first purified to produce aluminium oxide Al2O3

Question 11

Extraction of aluminium electrode equations

Answer 11

Negative electrode -
Al3+ + 3e- -> Al

Positive electrode -
2O2- -> O2 + 4e-

Question 12

Extraction of aluminium

What happens with some of the oxygen produced?

Answer 12

The oxygen reacts w the graphite (carbon) to produce CO2

C + O2 -> CO2

Therefore the positive electrode gradually burns away and needs to be replaced at regular intervals

Question 13

Extraction of iron raw materials

Answer 13

Iron ore (haematite)
Coke (carbon)
Limestone (calcium carbonate)
Air

Question 14

Extraction of iron process

Answer 14

Iron ore, Coke and limestone mixed together and fed into top of the blast furnace
Hot air is blasted into the bottom of the furnace
Oxygen in air reacts w Coke to form carbon dioxide
Carbon dioxide reacts w Coke to form carbon monoxide
Carbon monoxide reduces the iron oxide in the iron core
Iron melts and collects at bottom- tap

Question 15

Extraction of iron

How is calcium silicate formed?

Answer 15

Calcium carbonate in limestone decomposes to form calcium oxide
CaCO3 -> CaO + CO2

Calcium oxide reacts w silicon dioxide which is an impurity in the iron core, to form calcium silicate
CaO + SiO2 -> CaSiO3

The calcium silicate melts and collects as a molten slag on top of the molten iron which is then tapped off separately

Question 16

Aluminium uses

Answer 16

Aeroplane bodies
Overhead power cables
Saucepans
Food cans
Window frames 

Why?
High strength to weight ratio
Good conductor of heat and electricity 
Non toxic
Resists corrosion

Question 17

Iron uses

Answer 17

Car bodies
Iron nails
Ships, girders, bridges

Strong and withstands corrosion