Give reason to show [2] i) Al 2O 3 is an amphoteric oxide [1] ii) BaO 2 is a peroxide. [1]

Al₂O₃+2NaOHHeat2NaAlO₂+H₂O

Reaction of Al₂O₃ with NaOH (basic oxide behaviour)

Al₂O₃+6HClHeat2AlCl₃+3H₂O

Reaction of Al₂O₃ with HCl (acidic oxide behaviour)

i) $Al X_{2} O X_{3}$ is amphoteric because it reacts with both acids and bases to form salts and water. With acids (e.g., HCl), it behaves as a basic oxide: $Al X_{2} O X_{3} + 6 HCl 2 AlCl X_{3} + 3 H X_{2} O$ With bases (e.g., NaOH), it behaves as an acidic oxide: $Al X_{2} O X_{3} + 2 NaOH 2 NaAlO X_{2} + H X_{2} O$ This dual behavior defines amphoterism.

ii) $BaO X_{2}$ is a peroxide because it contains the peroxide ion ( $O X_{2} X^{2 -}$ ), where oxygen has an oxidation state of $- 1$ . This is confirmed by its reaction with acids (e.g., $H X_{2} SO X_{4}$ ) to produce hydrogen peroxide ( $H X_{2} O X_{2}$ ): $BaO X_{2} + H X_{2} SO X_{4} BaSO X_{4} + H X_{2} O X_{2}$ Peroxides release oxygen on heating, unlike normal oxides (e.g., $BaO$ ), which do not.

BaO₂+H₂SO₄HeatBaSO₄+H₂O₂

Decomposition of BaO₂ (peroxide) to release H₂O₂

Discussion

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