Explain the amphoteric nature of zinc oxide and aluminium oxide

1.	Explain the amphoteric nature of zinc oxide and aluminium oxide
Answer» Solution :On warming zinc oxide with dilute sulphuric, the zinc oxide dissolves rapidly and forms clear solution of zinc sulphate. Similarly, when aluminium oxide is warmed with dilute sulphuric acid forms aluminium sulphate. `ZnO + underset((dil))(H_(2)SO_(4)) RARR ZnSO_(4) + H_(2)O` `Al_(2)O_(3) + underset((dil))(3H_(2)SO_(4)) rarr Al_(2) (SO_(4))_(3) + 3H_(2)O` On warming zinc oxide with concentrated sodium hydroxide or potassium hydroxide, the zinc oxide rapidly dissolves to form clear solution of sodium zincate or potassium zincate. Similarly, aluminium oxide reacts with concentrated sodium hydroxide to form sodium metaluminate. `ZnO + 2NaOH rarr Na_(2)ZnO_(2) + H_(2)O` `Al_(2)O_(3) + 2NaOH rarr 2NaAlO_(2) + H_(2)O` As the oxides of zinc and aluminium react with acids as WELL as alkali to form salt and water, they are amphoteric in nature.

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