S5 - Extraction and uses of metals (iron)

Question 1

What is a raw material?

Answer 1

A natural resource that can be used to make a useful product.

Question 2

What is the main ore of iron, which is mainly iron (lll) oxide?

Answer 2

Hematite Fe3O2

Question 3

What are the four raw materials that go into a blast furnace?

Answer 3

Iron ore (Fe2O3)
Coke (C)
Limestone (CaCo3)
Preheated air

Question 4

What are the three things that come out of a blast furnace?

Answer 4

Molten iron
Molten slag
Waste gases

Question 5

What is the most abundant waste gas that comes out and why?

Answer 5

Nitrogen

It makes up 80% of the air that enters the furnace but does not react in the furnace.

Question 6

Why does molten slag float on top of molten iron?

Answer 6

Its less dense.

Question 7

How does the fact that molten slag floats on top of molten iron stop the iron reverting to reform iron (lll) oxide?

Answer 7

The molten iron is not in contact with the preheated air so will not get reoxidised by the oxygen in the preheated air.

Question 8

How is coke produced from the coal?

Answer 8

Heating coal in the absence of air.

Question 9

Write a chemical equation for the burning of coke in the air

Answer 9

C(s) + O2 (g) —> CO2 (g)

Question 10

Why is burning of coke in the air important in the blast furnace?

Answer 10

It produces heat for the other reactions in the furnace (which are all endothermic)

Question 11

Write the word and chemical equation for the decomposition of the limestone

Answer 11

Calcium carbonate —> calcium oxide + carbon dioxide

CaCo3 —> CaO + CO2

Question 12

Which impurity is removed by calcium oxide?

Answer 12

Silica/silicon dioxide

Question 13

What is name of the product formed by the reaction of the impurity with calcium oxide?

Answer 13

Slag/calcium silicate

Question 14

Write a word and chemical equation for the reactions of this impurity with calcium carbonate. What type of reaction is taking place?

Answer 14

Calcium oxide + silicon dioxide —> calcium silicate
CaO + SiO2 —> CaSiO3

Neutralisation

Question 15

What are the physical properties of iron if the impurity being removed by the limestone were not removed.

Answer 15

The iron would become brittle and break.

Question 16

Give two uses of slag

Answer 16

Road building - motorways

heat insulation blocks

Question 17

Where in the blast furnace does the reaction of coke and oxygen take place?

Answer 17

At the bottom where heat enters.

Question 18

What is the significance of the reaction between coke and oxygen?

Answer 18

It is exothermic and provides heat for the other reactions.

Question 19

Write a word and chemical equation for the reaction of carbon dioxide with coke

Answer 19

Carbon dioxide + Coke —> Carbon monoxide

CO2 (g) + C(s) —> 2CO(g)

Question 20

What is the function of the reaction of carbon dioxide with coke (include chemical equation)

Answer 20

Reducing agent
CO removes oxygen from the iron ore
3CO + Fe2O3 —> 2Fe + 3CO2

Question 21

Explain how the carbon content of the iron from the blast furnace is lowered to produce mild steel

Answer 21

High pressure oxygen is blown into the molten iron. It oxidises the carbon to carbon dioxide which then escapes.

Question 22

What is an alloy?

Answer 22

A mixture of metals or metals with non-metals

Question 23

Why is pure iron soft and malleable?

Answer 23

The electrons/ions can slide over one another.

Question 24

Why does alloying metals make them harder?

Answer 24

Alloying metal atoms are a different size to iron atoms and stop the layers from sliding past each other.

Question 25

Give a use for:

Stainless steel
Titanium steel
Mild Steel
Hard Steel

Answer 25

Stainless steel - cutlery
Titanium steel - bicycle frames
Mild Steel - car bodies
Hard Steel - chisels

Question 26

How does iron conduct electricity?

Answer 26

Delocalised electrons that move through the lattice when a potential is applied.