Question
Give reasons:
Aluminium utensils should not be kept in water overnight.
Aluminium utensils should not be kept in water overnight.
✓
Answer
Generally, aluminium metal does not react with water quickly but, when it is kept overnight, it reacts slowly with water in presence of air.
$2 \mathrm{Al}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{Al}_2 \mathrm{O}_3(\mathrm{~S})+\mathrm{H}_2(\mathrm{~g})$
a very small amount of (in ppm) $\mathrm{Al}^{3+}$ produced in the solution is injurious to health if the water is used for drinking purposes.
$2 \mathrm{Al}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{Al}_2 \mathrm{O}_3(\mathrm{~S})+\mathrm{H}_2(\mathrm{~g})$
a very small amount of (in ppm) $\mathrm{Al}^{3+}$ produced in the solution is injurious to health if the water is used for drinking purposes.
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