oxide metal recovered? lead oxide yes copper oxide yes iron oxide yes aluminium oxide no The diagram shows an experiment where a metal oxide is heated with ...
Question 1 Report
| oxide | metal recovered? |
|---|---|
| lead oxide | yes |
| copper oxide | yes |
| iron oxide | yes |
| aluminium oxide | no |
The diagram shows an experiment where a metal oxide is heated with carbon in a crucible and the metal is recovered. The table lists which oxides gave metal. Which metal oxide CANNOT be reduced by carbon?
Answer Details
Carbon can only remove oxygen from a metal oxide if the metal is below carbon in the reactivity series. If the metal is above carbon, it holds oxygen more strongly than carbon does and the reduction cannot happen.
The table shows metal recovered from lead oxide, copper oxide and iron oxide, all metals below carbon, for example \( 2\text{CuO} + \text{C} \rightarrow 2\text{Cu} + \text{CO}_2 \). Only aluminium oxide gives no metal, because aluminium is well above carbon; it is extracted instead by electrolysis of the molten oxide dissolved in cryolite.
The lesson is that heating harder will not help. The barrier is the reactivity order, not the temperature, so a different method is needed rather than a hotter crucible.
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