Question
Why should a magnesium ribbon be cleaned before burning in air?
✓
Answer
- Magnesium ribbon is more reactive and when it is exposed to air, a layer of $MgO$ is formed on its surface.
- $2 \mathrm{Mg}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{MgO}(\mathrm{s})$
- This layer of MgO is removed by rubbing with sand paper before burning in air. Therefore, magnesium ribbon easily reacts with oxygen.
- Thus, magnesium ribbon is cleaned before burning in air.
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