Question

In the following sets of reactants which two sets best exhibit the amphoteric character of $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O$ ?
Set1: $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O\left( s \right)$ and $O{{H}^{-}}$
Set2: $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O\left( s \right)$ and${{H}_{2}}O$
Set3: $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O\left( s \right)$ and ${{H}^{+}}$
Set4: $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O\left( s \right)$ and $N{{H}_{3}}$
A. 1 and 2
B. 2 and 4
C. 1 and 3
D. 3 and 4

Answer 1

Hint: As we know that amphoteric character is shown by a molecule that can react with both acid and a base. We can see here that $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O$ is a metal oxide of aluminium. Basically, amphoterism is found to be dependent on the oxidation states of the oxides.

Complete Solution :
- We have to find which two sets exhibit the amphoteric characters of $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O$. Those compounds that react with both acids and salt are known to exhibit amphoteric character. Basically, it is found that aluminium oxide is an inorganic salt used as an antacid.
- As we all know that aluminium oxide is an amphoteric oxide because it shows the properties of both basic as well as acidic oxides.
- It is found that it reacts with both acids and bases to form the corresponding salt and water.
\[A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O+2NaOH\to NaAl{{O}_{2}}+{{H}_{2}}O\]
\[A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O+HCl\to AlC{{l}_{3}}+{{H}_{2}}O\]

- Aluminium oxide is the most commonly used chemical as adjuvant and is used in vaccines.
- Hence, we can conclude that the correct option is (c) that is Set1: $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O\left( s \right)$ and $O{{H}^{-}}$, and Set3: $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O\left( s \right)$ and ${{H}^{+}}$ both sets best exhibit the amphoteric character of $A{{l}_{2}}{{O}_{3}}.x{{H}_{2}}O$.
So, the correct answer is “Option C”.

Note: - It is found that aluminium oxide can cause some side effects like vomiting, nausea, constipation. While it is used on a large scale in curing of diseases like sour stomach, relief from heartburn.