International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

Why isn't aluminium extracted in a blast furnace like iron?

1. Aluminium is more reactive than iron

2. Aluminium does not form oxides

3. Aluminium requires a different extraction method

4. Aluminium cannot withstand high temperatures

The correct answer is: Aluminium is more reactive than iron

Aluminium is extracted using the electrolytic method because it is more reactive than iron. This high reactivity means that aluminium has a stronger affinity for oxygen and is more difficult to separate from its oxide (in this case, bauxite, which primarily contains aluminium oxide). In a blast furnace, iron is reduced from its ore (iron oxide) using carbon at high temperatures. However, the energy required to reduce aluminium oxide and its strong bonds with oxygen make it impractical to use a blast furnace for aluminium extraction. Instead, the Hall-Héroult process is employed, which involves electrolysis, allowing for the use of lower temperatures in a controlled environment. The other options do not accurately represent the reason behind the extraction method used for aluminium. For instance, aluminium does indeed form oxides, and while it cannot withstand the conditions of a blast furnace as effectively as iron, the key factor remains its higher reactivity, necessitating a different extraction approach.