Question: Assertion: The pH of \[N{H_4}Cl\] solution in water is less than 7 and pH of \[C{H_3}COONa\] solutio...

Question

Assertion: The pH of $N{H_4}Cl$ solution in water is less than 7 and pH of $C{H_3}COONa$ solution is more than 7.
Reason:
$N{H_4}Cl$ is a salt of weak base $N{H_4}OH$ and strong acid $HCl$ whereas $C{H_3}COONa$ is a salt of a weak acid $C{H_3}COOH$ and strong base $NaOH$ .
A.Both Assertion and Reason are correct and Reason is the correct Explanation for Assertion.
B.Both Assertion and Reason are correct and Reason is not the correct Explanation for Assertion.
C.Assertion is correct but Reason is incorrect
D.Both Assertion and Reason are incorrect

Answer 1

Solution

We need to know and understand the concept of pH and also its relation to acids and bases. The pH scale is used to classify solutions based on their acidity or basicity (alkalinity). The pH scale is commonly stated to run from $0$ to $14$ , and most solutions do lie within this range, however it is conceivable to have a pH lower than $0$ or higher than $14$ . Anything less than $7.0$ is acidic, while anything greater than $7.0$ is alkaline, or basic.

Complete answer:
We have to know that ammonium chloride is a salt that is produced by combining ammonium hydroxide, a weak base, with hydrochloric acid, a strong acid. It will ionize and dissociate more when dissolved in water. $N{H_4}Cl$ when is dissolved in water, it breaks into its constituent ions which are $N{H^{4 + }}\& C{l^ - }$ . Since, it is made up of a strong acid $HCl$ and a weak base $N{H_4}OH$ . As a result, because it is composed of strong acid, it acts as an acid when dissolved in water, and acids have a pH less than $7$ . Similarly, $C{H_3}COONa$ is composed of a weak acid ( $C{H_3}COOH$ ) and a strong base ( $NaOH$ ). As a result, it acts as a basic salt in water and has a pH greater than $7$ .

Therefore, the correct option is option (A).

Note:
We must note that strong acid is any acid that completely dissociates into ions. It is a weak acid if it does not dissociate completely. The situation is identical with bases: a strong base is one that is completely ionised in solution. It is a weak base if it is less than completely ionised in solution. In aqueous solution, strong acids and bases are completely ionised. Weak acids and bases are not completely ionised in aqueous solution. The acidity or basicity of aqueous solutions can be affected by salts of weak acids or bases.