Question

Amphoteric oxide is:
A. $A{l}_2{O}_3$
B. $Si{O}_2$
C. $P_4{O}_{10}$
D. $Cl{O}_7$

Answer 1

Hint: Amphoteric oxide means, the metal oxide has a capability to react with both acid and base. Numerous metals like lead, beryllium aluminium and zinc form amphoteric oxides and they are highly reactive towards acid and bases.

Complete step by step answer:
- We have to find which chemical is amphoteric oxide among the given options.
- Among the given oxides aluminum oxide ($A{l}_2{O}_3$ ) only shows the property of reaction with both acid and base.
- The reaction of aluminium oxide with hydrochloric acid is as follows.
$$A{l}_2{O}_3+6HCl\to 2AlC{l}_3+3H_{2}O$$
- In the above reaction one mole of aluminium oxide reacts with 6 moles of hydrochloric acid and forms 2 moles of aluminium chloride and 3 moles of water as the products.
- The reaction of aluminium oxide with sodium hydroxide (base) is as follows.
$$A{l}_2{O}_3+2NaOH\to 2NaAl{O}_2+H_{2}O$$
- In the above reaction one mole of aluminium oxide reacts with 2 moles of sodium hydroxide and forms 2 moles of sodium aluminate and 1 mole of water as the products.
- Therefore aluminium oxide only reacts with both acid and base among the given options.

- So, the correct option is A.

Note: Like aluminium oxide zinc oxide also reacts with both acid and base. The reaction of zinc oxide with an acid and a base is as follows.
$$ZnO+2HCl\to ZnC{l}_2+H_{2}O$$
$$ZnO+2NaOH\to N{a}_{2}Zn{O}_2+H_{2}O$$
 In the above reaction one mole of zinc oxide reacts with 2 moles of an acid (HCl) and forms zinc chloride and one mole of zinc oxide reacts with two moles of sodium hydroxide (NaOH) and forms sodium zincate as the products.