Question

Explain why an aqueous solution of ammonium chloride is acidic in nature.

Answer 1

Before proceeding to the question let us first have a basic knowledge of ammonium chloride. The inorganic compound ammonium chloride $\left( {N{H_4}Cl} \right)$ is a white crystalline salt that is extremely soluble in water. Ammonium chloride solutions are moderately acidic.

Complete answer:
Because ammonium chloride $\left( {N{H_4}Cl} \right)$ is the salt of a strong acid, hydrochloric acid $(HCl)$ , and a weak base, ammonium hydroxide $\left( {N{H_4}OH} \right)$ , its aqueous solution is acidic.
Explanation:-
We'll look at how acidic it is in aqueous solution.
The ionisation of $\left( {N{H_4}Cl} \right)$ produces the $NH_4^ +$ ion and the $C{l^ - }$ ion. These ions react with the water molecule's ${H^ + }$ and $O{H^ - }$ ions to generate $N{H_4}OH$ and $HCl$ , respectively.
$N{H_4}Cl \to N{H_4} + C{l^ - }$
$N{H_4}OH \Leftrightarrow N{H_4} + O{H^ - }$
$HCl \to {H^ + } + C{l^ - }$
As demonstrated above, the $HCl$ molecule will completely ionise to generate the ${H^ + }$ ion.
However, as illustrated above, the $N{H_4}OH$ molecule only partially ionises. As a result, the ions present in the $\left( {N{H_4}Cl} \right)$ solution will be $NH_4^ +$ , $C{l^ - }$ , ${H^ + }$ , and $O{H^ - }$ . Aside from this, there will be some $N{H_4}OH$ that is unionised.
As previously stated, the quantity of ${H^ + }$ ions will exceed the number of $O{H^ - }$ ions. As a result, the $\left( {N{H_4}Cl} \right)$ Solution will be acidic.

Additional Information:
Ammonium chloride is most commonly used as a nitrogen source in fertilisers, such as chloro ammonium phosphate (which accounts for $90\%$ of global ammonium chloride production). Rice and wheat are the most common crops fed this manner throughout Asia.

Note:
Sal Ammoniac, commonly known as sal ammoniac or salmiak, is a rare naturally occurring mineral made up of ammonium chloride. In the isometric-hexoctahedral class, it produces colourless, white, or yellow-brown crystals. It has poor cleavage and is brittle enough to fracture conchoidally. It's a water-soluble substance. The chemical compound ammonium chloride is also known as sal ammoniac.