Iron and aluminium are two important metals extracted on a large scale.
In the extraction of iron, various raw materials and impurities are involved. Name the main chemical compound present in: (i) Limestone (ii) The major sandy impurity in the iron ore
The following chemical equations represent reactions occurring in a blast furnace: A C+O2→CO2\text{C} + \text{O}_2 \rightarrow \text{CO}_2C+O2→CO2 B CaCO3→CaO+CO2\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2CaCO3→CaO+CO2 C CO2+C→2CO\text{CO}_2 + \text{C} \rightarrow 2\text{CO}CO2+C→2CO D Fe2O3+3CO→2Fe+3CO2\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2Fe2O3+3CO→2Fe+3CO2 E CaO+SiO2→CaSiO3\text{CaO} + \text{SiO}_2 \rightarrow \text{CaSiO}_3CaO+SiO2→CaSiO3
Choose from the letters A, B, C, D or E to answer the following. Each letter may be used once, more than once, or not at all. (i) An acid-base reaction that removes acidic impurities (ii) A thermal decomposition reaction (iii) A highly exothermic reaction that maintains the high temperature of the furnace (iv) A reaction that produces a gaseous reducing agent
Molten iron and slag collect at the bottom of the blast furnace. State the chemical name of the main compound present in slag.
Aluminium is extracted from aluminium oxide by electrolysis. (i) Why cannot carbon be used to reduce aluminium oxide in a blast furnace? (ii) Explain the purpose of adding cryolite to the aluminium oxide during electrolysis.
During the extraction of aluminium by electrolysis, the carbon anodes have to be replaced periodically. Explain why.
The overall extraction of aluminium can be represented by the chemical equation:
2Al2O3→4Al+3O2 2\text{Al}_2\text{O}_3 \rightarrow 4\text{Al} + 3\text{O}_2 2Al2O3→4Al+3O2Write the two balanced ionic half-equations representing the reactions occurring at the electrodes.
Half-equation 1 (at the cathode): Half-equation 2 (at the anode):
