S5 - Extraction and uses of metals (iron) Flashcards
What is a raw material?
A natural resource that can be used to make a useful product.
What is the main ore of iron, which is mainly iron (lll) oxide?
Hematite Fe3O2
What are the four raw materials that go into a blast furnace?
Iron ore (Fe2O3)
Coke (C)
Limestone (CaCo3)
Preheated air
What are the three things that come out of a blast furnace?
Molten iron
Molten slag
Waste gases
What is the most abundant waste gas that comes out and why?
Nitrogen
It makes up 80% of the air that enters the furnace but does not react in the furnace.
Why does molten slag float on top of molten iron?
Its less dense.
How does the fact that molten slag floats on top of molten iron stop the iron reverting to reform iron (lll) oxide?
The molten iron is not in contact with the preheated air so will not get reoxidised by the oxygen in the preheated air.
How is coke produced from the coal?
Heating coal in the absence of air.
Write a chemical equation for the burning of coke in the air
C(s) + O2 (g) —> CO2 (g)
Why is burning of coke in the air important in the blast furnace?
It produces heat for the other reactions in the furnace (which are all endothermic)
Write the word and chemical equation for the decomposition of the limestone
Calcium carbonate —> calcium oxide + carbon dioxide
CaCo3 —> CaO + CO2
Which impurity is removed by calcium oxide?
Silica/silicon dioxide
What is name of the product formed by the reaction of the impurity with calcium oxide?
Slag/calcium silicate
Write a word and chemical equation for the reactions of this impurity with calcium carbonate. What type of reaction is taking place?
Calcium oxide + silicon dioxide —> calcium silicate
CaO + SiO2 —> CaSiO3
Neutralisation
What are the physical properties of iron if the impurity being removed by the limestone were not removed.
The iron would become brittle and break.
Give two uses of slag
Road building - motorways
heat insulation blocks
Where in the blast furnace does the reaction of coke and oxygen take place?
At the bottom where heat enters.
What is the significance of the reaction between coke and oxygen?
It is exothermic and provides heat for the other reactions.
Write a word and chemical equation for the reaction of carbon dioxide with coke
Carbon dioxide + Coke —> Carbon monoxide
CO2 (g) + C(s) —> 2CO(g)
What is the function of the reaction of carbon dioxide with coke (include chemical equation)
Reducing agent
CO removes oxygen from the iron ore
3CO + Fe2O3 —> 2Fe + 3CO2
Explain how the carbon content of the iron from the blast furnace is lowered to produce mild steel
High pressure oxygen is blown into the molten iron. It oxidises the carbon to carbon dioxide which then escapes.
What is an alloy?
A mixture of metals or metals with non-metals
Why is pure iron soft and malleable?
The electrons/ions can slide over one another.
Why does alloying metals make them harder?
Alloying metal atoms are a different size to iron atoms and stop the layers from sliding past each other.
Give a use for:
Stainless steel
Titanium steel
Mild Steel
Hard Steel
Stainless steel - cutlery
Titanium steel - bicycle frames
Mild Steel - car bodies
Hard Steel - chisels
How does iron conduct electricity?
Delocalised electrons that move through the lattice when a potential is applied.
