metal method aluminium electrolysis zinc carbon reduction iron carbon reduction copper carbon reduction The ladder shows metals and the table shows extracti...
Question 1 Report
| metal | method |
|---|---|
| aluminium | electrolysis |
| zinc | carbon reduction |
| iron | carbon reduction |
| copper | carbon reduction |
The ladder shows metals and the table shows extraction methods. A metal extracted by electrolysis is more reactive than one extracted with carbon. Which metal, shown on the ladder, is extracted by electrolysis?
Answer Details
The extraction method depends on where a metal stands relative to carbon. Zinc, iron and copper all sit below carbon, so heating their oxides with carbon reduces them cheaply, for example \[\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}\]
Aluminium is the metal extracted by electrolysis. It lies above carbon in the reactivity series, so carbon cannot take its oxygen away. Molten aluminium oxide dissolved in cryolite is electrolysed instead, and aluminium ions gain electrons at the cathode: \[\text{Al}^{3+} + 3\text{e}^{-} \rightarrow \text{Al}\]
Students often assume the most expensive or the most common metal is electrolysed. The deciding factor is only reactivity: above carbon means electrolysis, below carbon means reduction with carbon.
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