Extraction And Uses Of Metals Maud

Question 1

When is the method of heating the ore with carbon or carbon monoxide used?

Answer 1

When a metal is less reactive than zinc

Question 2

What is electrolysis used for

Answer 2

Extracting metals that are more reactive than zinc

Question 3

The name of aluminium’s ore?

Answer 3

Bauxite

Question 4

What is bauxite

Answer 4

Impure aluminium oxide

Question 5

Equation for aluminium ions being reduced to aluminium?

Answer 5

Al 3+ + 3e- –> Al

Question 6

Equation for oxygen ions forming oxygen gas?

Answer 6

2O 2- –> O2 + 4 e-

Question 7

How does bauxite become aluminium and oxygen?

Answer 7

The aluminium ions are attracted to the cathode and are reduced to aluminium

Oxygen ions are attracted to the anode and lose electrons to form oxygen gas

Question 8

What is aluminium oxide dissolved in and why?

Answer 8

It is dissolved in an aluminium compound called cryolite as a flux to lower its melting point

Melting aluminium oxide requires extremely high temperatures

Question 9

Why do the anodes have to be replaced regularly?

Answer 9

Because of the high temperatures, the carbon anodes will burn with the oxygen produced to form carbon dioxide.

Question 10

What currents do the cells have?

What does this mean?

Answer 10

Currents up to 100 000

This means it is expensive

Question 11

Why is aluminium good for making aircraft with?

Answer 11

Resists corrosion due to its aluminium oxide coat

Has low density

Strong

Question 12

Why is aluminium good for making saucepans with?

Answer 12

Keeps its shiny appearance

Good conductor of heat

Resists corrosion

Low density

Question 13

Why does aluminium resist corrosion?

Answer 13

Because of its tenacious oxide layer

Question 14

What method is used to extract aluminium?

Answer 14

Electrolysis

Question 15

What method is used to extract iron?

Answer 15

The blast furnace

Question 16

What is the name of irons ore?

Answer 16

Haematite

Question 17

What is haematite?

Answer 17

An ore that contains iron (III) oxide

Question 18

What is coke and what is it used for?

Answer 18

Coke is impure carbon that burns to form carbon dioxide

It is used to heat the blast furnace as burning it is a strongly exothermic reaction.

Question 19

Blast furnace

Carbon to CO2?

Answer 19

C + O2 –> CO2

Question 20

At high temperatures, what happens to the carbon dioxide formed by coke?
Equation?

Answer 20

The carbon dioxide is reduced by more carbon to give carbon monoxide

C + CO2 –> 2CO

Question 21

What does carbon monoxide do in the blast furnace?

Equation?

Answer 21

It is the main reducing agent

Fe2O3 + 3CO –> 2Fe + 3CO2

Question 22

What is the other reducing agent other than carbon monoxide?

Reaction?

Answer 22

Carbon

Fe2O3 + 3C –> 2Fe + 3CO

Question 23

What happens to the limestone in the furnace?

Equation?

Answer 23

The heat of the furnace causes the limestone to thermally decompose form calcium oxide and carbon dioxide

CaCO3 –> CaO + CO2

Question 24

What happens to the calcium oxide in the blast furnace?

Answer 24

The calcium oxide reacts with acidic silicon dioxide(sand). SiO2 is one of the impurities found in haematite.

Molten calcium silicate is formed and trickles to the bottom of the furnace as molten slag

SiO2 + CaO –> CaSiO3(slag)

Question 25

What goes in at the top of the blast furnace?

Answer 25

Iron ore, coke and limestone

Question 26

What comes out at the top of the blast furnace?

Answer 26

Hot waste gases

Question 27

What is the blast furnace made from?

Answer 27

Steel lines with heat resistant brick

Question 28

What are electrolysis tanks made from?

Answer 28

Steel lined with refractory brick

Question 29

What is the temperature range in the blast furnace?

Answer 29

400-1800 degrees

Question 30

What goes in at the bottom of the blast furnace?

Answer 30

Hot air is blasted in

Question 31

What comes out at the bottom of the blast furnace?

Answer 31

Molten slag and below that molten (iron)

Question 32

Types of iron?

Answer 32

``` Wrought iron Mild steel High-carbon steel Cast iron Stainless steel ```

Question 33

Wrought iron (what mixed with, properties and uses?)

Answer 33

Pure iron Very soft Decorative work such as gates and railings

Question 34

Mild steel (what mixed with, properties and uses?)

Answer 34

0.25% carbon Tough, malleable Nails, car bodies and ship building

Question 35

High-carbon steel (what mixed with, properties and uses?)

Answer 35

0.25 - 1.5% carbon Hard Cutting tools

Question 36

Cast iron (what mixed with, properties and uses?)

Answer 36

About 4% carbon Very brittle but strong Manhole covers Guttering Engine blocks

Question 37

Stainless steel (what mixed with, properties and uses?)

Answer 37

Chromium and nickel Resists rusting Expensive Cutlery Cooking utensils

Question 38

Ways of preventing the rusting of iron?

Answer 38

Using barriers Alloying the iron Using sacrificial anodes

Question 39

Using barriers to prevent the rusting of iron?

Answer 39

Keep water / oxygen away from the iron by painting / coating it with oil e.t.c

Question 40

Alloying the iron to prevent it rusting?

Answer 40

Such as allowing it with chromium and nickel to produce stainless steel

Question 41

Using sacrificial anodes to prevent iron rusting?

Answer 41

Galvanising iron by coating it with a layer of zinc Zinc is more reactive than Iron and will corrode instead During the process it loses electrons to form ions These electrons flow into the iron so any iron atom which has lost electrons immediately regains them These mean that even if the zinc is scratched, the iron won't rust