Explain the process of iron extraction in a blast furnace and the properties and uses of the resulting iron and steel.

a) The constituents of A are limestone, coke, and iron ore.

b) You would expect the highest temperature at point H.

c) The role of the hot air blasts is to:

• Provide oxygen for the combustion of coke, which produces the high temperatures needed and forms carbon dioxide.
• The carbon dioxide then reacts with more hot coke to produce carbon monoxide, which acts as the reducing agent for the iron ore.

d) Yes, it is possible to separate iron from the slag. This is because molten iron and molten slag are immiscible (do not mix) and have different densities. The slag is less dense and floats on top of the molten iron, allowing them to be tapped off separately.

e) The main reaction that takes place to produce iron is:

$$\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \to 2\text{Fe(l)} + 3\text{CO}_2\text{(g)}$$

f) Iron obtained from the furnace (pig iron) contains a high percentage of carbon (about 4%) and other impurities, making it hard and brittle. For building bridges, a material that is strong, tough, and ductile is required. Therefore, pig iron must be further treated to remove most of the carbon and other impurities to produce steel, which has these desired properties.

g) Galvanized iron is iron or steel that has been coated with a protective layer of zinc.

h) It is necessary to galvanize iron to prevent it from rusting (corrosion). The zinc coating acts as a physical barrier and also provides sacrificial protection, meaning the zinc corrodes preferentially to the iron if the coating is scratched.

i) One environmental hazard associated with the extraction of iron is air pollution, specifically the release of carbon dioxide (a greenhouse gas) and sulfur dioxide (which contributes to acid rain) from the combustion of coke and impurities.