Question

An aqueous solution of $0.1M$ $N{H_4}Cl$ will have a $pH$ closer to:
a.) $9.1$
b.) $8.1$
c.) $7.1$
d.) $5.1$

Answer 1

Hint: The given compound is ammonium chloride and it is a salt of strong acid $HCl$ and a weak base $N{H_4}OH$, and we know that the compounds which are able to give acidic solution on hydrolysis they are in acidic in nature and the $pH$ value of the acidic solution are below the $pH$ value of $7$.

Complete step by step solution:

On the hydrolysis of the ammonium chloride the ammonium chloride firstly decomposes into its component ions that are $N{H_4}^ +$ and $C{l^ - }$.
$N{H_4}Cl(solid)\xrightarrow{{{H_2}O}}N{H_4}^ + (aqueous) + C{l^ - }(aqueous)$ ----equation (1)
Now the aqueous $N{H_4}^ +$ with the water will give $N{H_4}^ +$and the $C{l^ - }$ will combine with the ${H^ + }$ ion of the water to form ${\text{HCl}}$ which is strong acid and this will result the solution to be acidic.
$C{l^ - } + {H_2}O \to HCl + {H_2}O$
Thus, the solution is acidic and we all know that the $pH$ value of acidic solution will always be less than $7$.
On looking at the option, we see that the only option (D) is having a value less than $7$ that is $5.1$.
Hence the $pH$ value of the aqueous solution of the ammonium chloride is $5.1$
So, option (D) is the correct answer.

Note: The presence of the ammonium chloride in a solution or in a reaction can be identified by some practical activity. Since the ammonium chloride is having ammonium ions in its solution then if we can identify the presence of the ammonium ions then we can confirm the presence of the ammonium chloride will be confirmed. To confirm the presence of the ammonium ion we add some appropriate amount of the dilute sodium hydroxide to the solution and then start heating the whole solution then the choking smell will show the presence of the evolution of ammonia gas will confirm the presence of the ammonium ion and ammonium chloride.