Question

A metal $A$, which is used in thermite process, when heated with oxygen gives an oxide $B$, which is amphoteric in nature. Oxide $B$ is:

• A. $2AlC{l}_3$
• B. $A{l}_2{O}_3$
• C. $NaAl{O}_2$
• D. $MgO$

Answer 1

Answer: (B)

$A{l}_2{O}_3$

Some displacement reactions are highly exothermic. The amount of heat evolved is so large that the metals are produced in the molten state. These reactions are known as thermite reaction and the process is called a thermite process. We know that Aluminium and Iron are used in a thermite process however only aluminium when heated with oxygen, gives aluminium oxide, which is an amphoteric substance, meaning it can react with both acids and bases. Thus, $A$ is aluminium and $B$ is aluminium oxide.
Reaction of aluminium oxide with hydrochloric acid can be written as follows:
$A{l}_2{O}_3+6HCl\to 2AlC{l}_3+3H_{2}O$
Reaction of aluminium oxide with sodium hydroxide can be written as follows:
$A{l}_2{O}_3+2NaOH\to 2NaAl{O}_2+H_{2}O$