(a) Which metal is extracted from bauxite ore?
(b) Give the name of one ore of iron. Which iron compound is present in this ore? Write its chemical formula.
(c) Describe the extraction of zinc metal from its sulphide ore (zinc blende). Write equations of the reactions involved.
(d) Explain why, the galvanised iron article is protected against rusting even if the zinc layer is broken.
(e) Name a common metal which is highly resistant to corrosion.
(a) Aluminium.
(b) Haematite; Iron (III) oxide, Fe2O3
(c) Zinc sulphide (zinc blende ore) is strongly heated in air (roasted), it forms zinc oxide and sulphur dioxide. This process is called roasting.
2ZnS(s) + 3O2(g) → Roasting 2ZnO(s) + 2SO2(g)
Then, zinc oxide is heated with carbon to form zinc metal.
ZnO(s) + C(s) → Zn(s) + CO(g)
(d) The galvanized iron object remains protected against rusting even if a break occurs in the zinc layer because zinc is more easily oxidised than iron. Hence, the zinc continues to corrode but iron object does not corrode or rust.
(e) Aluminium.