What is the pH of ${\mathrm{NH}}_4\mathrm{Cl}$?

Part 1: pH

• The pH of any solution is defined as the negative log of Hydrogen ion concentration.
• Mathematically, $\mathrm{pH}=-{\log }_{10}\left[{\mathrm{H}}^{+}\right]$
• pH is used to determine the nature of the solution whether it is acidic, basic, or neutral.

Solution	pH range
Acidic	1 - 6.9
Neutral	7
Basic	7.1 - 14

Part 2: Identifying the pH of the Ammonium chloride

• The corresponding acid and base of salt can be produced by the hydrolysis of salt.
• The hydrolysis reaction can be represented as:

$\underset{\mathrm{Ammonium}\mathrm{chloride}}{{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Ammonium}\mathrm{hydroxide}}{{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)}$

• Therefore, Ammonium chloride is an acidic salt that is formed by the neutralization of hydrochloric acid by a weak base Ammonium hydroxide.
• Hence, the pH of Ammonium chloride lies in the slightly acidic range.
• Hence, pH value of ammonium chloride lies in the range of 4.5 to 6.