Question

The salt that gives a neutral solution when dissolved in water is:

• A. ${\mathrm{Na}}_2{\mathrm{SO}}_4$
• B. ${\mathrm{NH}}_4\mathrm{Cl}$
• C. ${\mathrm{CH}}_3\mathrm{COONa}$
• D. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

Answer 1

The correct option is A

${\mathrm{Na}}_2{\mathrm{SO}}_4$

Explanation for the correct option:

(A) ${\mathrm{Na}}_2{\mathrm{SO}}_4$

1. Neutral salts are formed when strong acids and strong bases react with each other.
2. Acidic salts are formed when strong acids and weak bases react with each other.
3. Basic salts are formed when weak acids and strong bases react with each other.
4. Sodium sulphate $\left({\mathrm{Na}}_2{\mathrm{SO}}_4\right)$is a combination of strong acid i.e., sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$, and a strong base Sodium hydroxide $\left(\mathrm{NaOH}\right)$.
5. The strong acid and strong base neutralize each other and form a neutral salt.
6. When Sodium sulphate dissolves in water it gives a neutral solution because the ${\mathrm{Na}}_2{\mathrm{SO}}_4$ is a neutral salt.

Reaction involved:

$2\mathrm{NaOH}\left(\mathrm{aq}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\stackrel{}{\to }{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Explanation for the incorrect options:

(B) ${\mathrm{NH}}_4\mathrm{Cl}$

1. Ammonium chloride $\left({\mathrm{NH}}_4\mathrm{Cl}\right)$ is a combination of a strong acid i.e., Hydrochloric acid $\left(\mathrm{HCl}\right)$ and a weak base Ammonium hydroxide $\left({\mathrm{NH}}_4\mathrm{OH}\right)$.
2. Therefore the salt formed is acidic.

(C) ${\mathrm{CH}}_3\mathrm{COONa}$

1. Sodium acetate $\left({\mathrm{CH}}_3\mathrm{COONa}\right)$ is a combination of weak acid i.e., acetic acid $\left({\mathrm{CH}}_3\mathrm{COOH}\right)$ and strong base $\mathrm{NaOH}$.
2. Therefore the salt formed is basic.

(D) ${\mathrm{Na}}_2{\mathrm{CO}}_3$

1. Sodium carbonate $\left({\mathrm{Na}}_2{\mathrm{CO}}_3\right)$ is a combination of weak acid carbonic acid $\left({\mathrm{H}}_2{\mathrm{CO}}_3\right)$ and a strong base sodium hydroxide $\left(\mathrm{NaOH}\right)$.
2. Therefore the salt formed is basic.

Hence, the correct option is (A).