Question

A salt derived from a strong acid and weak base will dissolve in water to give a solution that is

• A. acidic
• B. basic
• C. neutral
• D. none of these

Answer 1

The correct option is A

acidic

Explanation for the correct option:

A:

• When a base and acid react with each other, they produce a salt & water. This reaction is called neutralization reaction, because it involves the combination between hydrogen ions [H⁺] of the acid and hydroxide ions [OH^-] of the base to form water.
• A salt derived from a strong acid and weak base will be acidic due to the presence of strong acid.
• When the salt will dissolve in water, it will give a solution that is acidic due to the presence of more hydronium ions $\left[{\mathrm{H}}_3{\mathrm{O}}^{+}\right]$ than hydroxyl ions$\left[{\mathrm{OH}}^{-}\right]$.
• For example, HCl is a strong acid and ammonium hydroxide $\left(\mathrm{N}{\mathrm{H}}_4\mathrm{O}\mathrm{H}\right)$ is a weak base, they produce ammonium chloride, acidic salt. When the salt dissolved in water, it gives hydrogen chloride (HCl), a strong acid and ammonium hydroxide, a weak base thus, the solution becomes acidic.
• The reaction is: $\underset{\left(\mathrm{Ammonium}\mathrm{chloride}\right)}{{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Hydrogen}\mathrm{chloride})}{\mathrm{HCl}\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Ammonium}\mathrm{hydroxide}\right)}{{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)}$

Explanation of the incorrect options

B: A salt of weak acid and strong base is basic and when it is dissolved in water, the resultant solution will become basic. For example, sodium acetate (CH₃COONa)

C: A solution of strong acid and strong base is neutral and when it is dissolved in water, the resultant solution will become neutral. For example sodium chloride (NaCl)

Hence, the correct option is (A), a salt derived from a strong acid and weak base will dissolve in water to give a solution that is acidic.