5. Give reason for the following:
(a) Aluminium oxide is considered as an amphoteric oxide.
(b) lonic compounds conduct electricity in molten state.
Answers
Answer:
Aluminium oxide reacts with both acidic and basic substances to give neutralization reaction and hence cannot be called a true acid as well as base. Hence it is called amphoteric oxide.
Al
2
O
3
+6HCl→2AlCl
3
+3H
2
O>> Neutralisation Reaction with hydrochloric acid ( behaves like a base )
Al
2
O
3
+2NaOH→2NaAlO
2
+H 2
O>> Neutralisation reaction with Sodium hydroxide ( behave like an acid )
(b) lonic compounds are bound to each other with strong attraction force. Hence they are in solid form and their ions are not mobile. When in molten state the ions become mobile and act as carriers for charge and hence conduct electricity.
Explanation:
Aluminium oxide is termed as an amphoteric oxide as it shows chemical reactivity with both acids as well as bases.In some case,it behaves as a basic oxide and reacts with an acid to from salt and water whereas in other cases,it reacts with a base to produce the same.