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Question
A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH.
Solution
Aluminium metal is used in the thermite reaction. When aluminium is heated with oxygen it gives a chemical compound aluminium oxide. Aluminium oxide is amphoteric in nature thus, it acts both as acid and base.
Hence, metal A is aluminium and oxide B is aluminium oxide.
`4"Al"("s") + 3"O"_2("s") -> 2"Al"_2"O"_3("s")`
`"Al"_2"O"_3("s") + 6"HCl"("aq") -> 2"AlCl"_3("aq") + 3"H"_2"O"("g")`
`"Al"_2"O"_3("s") + 2"NaOH"("aq") -> 2"NaAlO"_2("aq") + "H"_2"O"("l")`
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