Section 5 - Pgs 66-69

Question 1

Why are most metals found in ores?

Answer 1

They are reactive so they easily form compounds - they are the ores.

Question 2

What is a metal ore?

Answer 2

A compound found in the Earth’s crust from which a metal can be extracted.

Question 3

What determines how easily a metal is extracted from its ore?

Answer 3

The more reactive the metal, the harder it is to extract from a compound.

Question 4

What is a common compound type for metal ores?

Answer 4

Oxides

Question 5

What is the extraction of a metal from its oxide ore called?

Answer 5

Reduction

Question 6

What is the name for the chemical used to extract a metal from its oxide ore?

Answer 6

The reducing agent

Question 7

What determines the way in which a metal is extracted from its ore?

Answer 7

• If it is less reactive than carbon, it is heated with carbon to remove the oxygen
• If it is more reactive than carbon, electrolysis is used

Question 8

Why must aluminium be extracted using electrolysis?

Answer 8

It is more reactive than carbon, so the carbon will not ‘steal’ the oxygen from the aluminium.

Question 9

What is the formula for aluminium ore?

Answer 9

Al2O3

Question 10

What is aluminium ore called?

Answer 10

Bauxite (Aluminium oxide)

Question 11

What is the melting point of aluminium oxide?

Answer 11

Over 2000*C

Question 12

What is cryolite used for in aluminium extraction and why?

Answer 12

It is used to dissolve the aluminium oxide in. This is because it has a lower melting point (about 900*C) so it saves energy.

Question 13

What is cryolite?

Answer 13

Another more rare aluminium ore, which has a lower melting point than aluminium oxide.

Question 14

By what process is aluminium extracted?

Answer 14

Electrolysis

Question 15

What are the electrodes in electrolysis made from?

Answer 15

Graphite

Question 16

What happens at the anode during the extraction of aluminium from aluminium oxide by electrolysis?

Answer 16

• O2- ions lose electrons to become O2 molecules

- These then react with the graphite anode to become CO2

Question 17

What happens at the cathode during the extraction of aluminium from aluminium oxide by electrolysis?

Answer 17

• Al3+ ions gain electrons to become Al atoms

- These then sink to the bottom

Question 18

Why does the anode need to be replaced frequently during the electrolysis of aluiminium oxide?

Answer 18

The oxygen formed there reacts with the carbon to form CO2, which is wears down the anode.

Question 19

What type of reaction is the electrolysis of aluminium oxide?

Answer 19

Redox

Question 20

What is the half-equation for the anode during the electrolysis of aluminium oxide?

Answer 20

2O2- -> O2 + 4e-

Question 21

What is the half-equation for the cathode during the electrolysis of aluminium oxide?

Answer 21

Al3+ + 3e- -> Al

Question 22

At which electrodes do oxidation and reduction happen during the electrolysis of aluminium oxide?

Answer 22

Oxidation: Anode
Reduction: Cathode

Question 23

Give the word eqauation for the decomposition of aluminium oxide by electrolysis.

Answer 23

Aluminium oxide -> Aluminium + Oxygen

Question 24

Why is electrolysis so expensive?

Answer 24

• It requires electricity
• Lots of heat needed to melt cryolite (900*C)
• Replacing anode

Question 25

What is the melting point of cryolite?

Answer 25

900*C

Question 26

How is iron extracted?

Answer 26

Reduction using carbon in a blast furnace.

Question 27

What is iron ore called?

Answer 27

Haematite (Iron oxide)

Question 28

What is the formula for iron ore?

Answer 28

Fe2O3

Question 29

What are the raw materials used in a blast furnace?

Answer 29

- Iron ore - Coke - Limestone (- Hot air)

Question 30

What is coke?

Answer 30

Almost pure carbon

Question 31

What is the chemical name for limestone?

Answer 31

Calcium carbonate

Question 32

What is the forumla for limestone?

Answer 32

CaCO3

Question 33

Remember to look at all the reactions in the blast furnace.

Answer 33

Pg 68 of revision guide

Question 34

What are the products of the blast furnace?

Answer 34

- Molten iron - Slag - Waste gases

Question 35

Give the reactions in the blast furnace.

Answer 35

``` Reducing the iron ore to iron: • C + O2 -> CO2 • CO2 + C -> 2CO • 3CO + Fe2O3 -> 3CO2 +2Fe Removing the impurities: • CaCO3 -> CaO + CO2 • CaO + SiO2 -> CaSiO3 ```

Question 36

What is the temperature in the blast furnace?

Answer 36

About 1500*C

Question 37

Give the reactions in the blast furnace used to reduce the iron ore.

Answer 37

* C + O2 -> CO2 * CO2 + C -> 2CO * 3CO + Fe2O3 -> 3CO2 +2Fe

Question 38

Give the reactions in the blast furnace used to remove impurities.

Answer 38

* CaCO3 -> CaO + CO2 | * CaO + SiO2 -> CaSiO3

Question 39

Where are slag and iron collected from the blast furnace?

Answer 39

At the bottom, because they are very dense and sink to the bottom.

Question 40

What is the formula for slag?

Answer 40

CaSiO3

Question 41

What does limestone decompose into in the blast furnace?

Answer 41

Calcium oxide and carbon dioxide

Question 42

What is the main impurity which needs to be removed in the blast furnace?

Answer 42

Sand

Question 43

What is the chemical name and formula for sand?

Answer 43

Silicon dioxide (SiO2)

Question 44

What are some uses of slag?

Answer 44

* Road-building | * Fertiliser

Question 45

What are some common properties of iron and aluminium?

Answer 45

* Dense * Lustrous * High melting points * Strong * Malleable * Good conductors of electricity and heat

Question 46

What is the melting point of iron?

Answer 46

1538*C

Question 47

What is the melting point of aluminium?

Answer 47

660*C

Question 48

What are the different forms of iron?

Answer 48

* Wrought iron * Cast iron * Steel * Stainless steel

Question 49

What is wrought iron and what are its properties and uses?

Answer 49

Almost pure iron -> Malleable | • Ornamental gates and railings

Question 50

What is cast iron and what are its properties and uses?

Answer 50

Mixture of iron, carbon and silicon -> Hard but brittle • Manhole cover • Some cooking pans

Question 51

What is steel and what are its properties and uses?

Answer 51

Mixture of iron, carbon and some other metals -> Hard but malleable • Car bodies • Girders

Question 52

What is stainless steel and what are its properties and uses?

Answer 52

Mixture of iron and chromium -> Doesn't rust • Knives and forks • Cooking pans

Question 53

What is the main problem with iron and how is this solved?

Answer 53

It rusts easily, which is solved by making stainless steel.

Question 54

What is wrought iron made from and what are its properties?

Answer 54

Almost pure iron -> Malleable

Question 55

What is cast iron made from and what are its properties?

Answer 55

Mixture of iron, carbon and silicon -> Hard but brittle

Question 56

What is steel made from and what are its properties?

Answer 56

Mixture of iron, carbon and some other metals -> Hard but malleable

Question 57

What is stainless steel made from and what are its properties?

Answer 57

Mixture of iron and chromium -> Doesn't rust

Question 58

What are the main differences between the properties of iron and aluminium?

Answer 58

* Aluminium does not corrode as easily as iron. | * Aluminium is lighter than iron.

Question 59

How do aluminium's properties determine its uses?

Answer 59

* Aluminium is light -> Bicycle frames + aeroplanes | * Aluminium doesn't corrode easily -> Drinks cans

Question 60

Why doesn't aluminium corrode easily?

Answer 60

The aluminium reacts very quickly with the oxygen in the air to form a protective layer of aluminium oxide, which prevents any further corrosion.