Question

$NaHC{{O}_{3}}$ is amphoteric in nature because:
(a)- It provides ${{H}^{+}}$ ions
(b)- It gains ${{H}^{+}}$ ions
(c)- Its aqueous solution is amphoteric
(d)- Both (a) and (b)

Answer 1

Hint: Amphoteric means the compound has the ability to act as an acid with a base and base with an acid. There are two reactions of $NaHC{{O}_{3}}$, one in which sodium ion, carbonate ion, and hydronium ion are formed, and the second in which sodium ions, carbonic acid, and hydroxyl ions are formed.

Complete step by step answer:
- The compound $NaHC{{O}_{3}}$ is known as sodium bicarbonate is a basic compound but it can act as an amphoteric compound. Amphoteric means the compound has the ability to act as an acid with a base and base with an acid.
- The sodium bicarbonate can react with water in two ways: one by accepting a proton from water and second by donating a proton to water.
(I)- When the carbonate accepts a proton from water, there is the formation of three types of ions i.e., sodium ions, carbonic acid, and hydroxyl ions. This reaction is more favored than the other due to which the solution is a little basic. The reaction is given below:
$NaHC{{O}_{3}}+{{H}_{2}}O\rightleftharpoons N{{a}^{+}}+{{H}_{2}}C{{O}_{3}}+O{{H}^{-}}$
(II)- When the carbonate donates a proton to water, there is the formation of three types of ions i.e., sodium ion, carbonate ion, and the hydronium ion. This reaction can make the solution acidic. The reaction is given below:
$NaHC{{O}_{3}}+{{H}_{2}}O\rightleftharpoons N{{a}^{+}}+CO_{3}^{2-}+{{H}_{3}}{{O}^{+}}$
The correct option is option “D” .

Note: $NaHC{{O}_{3}}$ is also known as sodium hydrogen carbonate and it is commonly known as baking soda which is used in making cakes, bread, etc. It is a white crystalline solid but it is also fine powder.