Question

Identify the acid and the base from which sodium chloride is obtained. Which type of salt is it? When is it called rock salt? How is rock salt formed?

Answer 1

Part 1: Identify the acid and base that form Sodium Chloride ($\mathbf{NaCl}$)

• Salt hydrolysis is a process in which salt reacts with water to give back the acid and base from which that salt is formed.
• The salt hydrolysis of Sodium chloride produces the base sodium hydroxide and Hydrochloric acid.
• The balanced chemical reaction of salt hydrolysis can be written as:

$\underset{\mathrm{Sodium}\mathrm{chloride}}{\mathrm{NaCl}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Sodium}\mathrm{Hydroxide}}{\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}$

• Hence, the acid and base are Hydrochloric acid and Sodium hydroxide respectively.

Part 2: Identify the nature of Sodium Chloride

• Sodium chloride is formed by the complete neutralization of a strong Hydrochloric acid by a strong base Sodium hydroxide.
• Hence, Sodium chloride is a neutral salt.

Part 3: Sodium Chloride as rock salt

• Sodium Salt is a neutral salt. It is also known as rock salt in crystalline form.
• It is the result of the evaporation of ancient oceans millions of years ago.
• Rock salt, also known as halite, is a type of salt that is the mineral component of Sodium chloride $\left(\mathrm{NaCl}\right)$.
• The acid used is Hydrochloric acid ($\left(\mathrm{HCl}\right)$ and base is Sodium hydroxide ($\mathrm{NaOH}$).
• Chemical Reaction involved:

$\underset{\mathrm{Hydrochloric}\mathrm{Acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Sodium}\mathrm{Hydroxide}}{\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Sodium}\mathrm{Chloride}}{\mathrm{NaCl}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)}$

• Rock Salt crystallizes in isometric shapes. It is sodium chloride in its impure form, crystallized, and mineral structure.

Therefore, Rock Salt is the mineral component of Sodium chloride, the acid, and base used are Hydrochloric acid $\left(\mathrm{HCl}\right)$ and Sodium hydroxide ($\mathrm{NaOH}$).