Why different methods are applied to extract iron and aluminum from their ores?
The oxidation of iron is destructive - iron oxide (rust) flakes off. The oxidation of aluminum is constructive - aluminum oxide forms a protective coat over the aluminum being oxidized. This means that electrolysis is suitable for extracting aluminum, but not iron. The 'blast furnace' method of extracting iron from its ore uses C in a series of reaction which leads to the reduction of the the iron oxide to iron. This will not work for aluminum because it is too high in the electrochemical series and consequently the ore is more stable, making the activation energy for the reaction far too high.
The oxidation of iron is destructive - iron oxide (rust) flakes off. The oxidation of aluminum is constructive - aluminum oxide forms a protective coat over the aluminum being oxidized. This means that electrolysis is suitable for extracting aluminum, but not iron. The 'blast furnace' method of extracting iron from its ore uses C in a series of reaction which leads to the reduction of the the iron oxide to iron. This will not work for aluminum because it is too high in the electrochemical series and consequently the ore is more stable, making the activation energy for the reaction far too high.
