The Acid & Base Components of Ammonium Chloride

Aqueous Ammonium Chloride

• Ammonium chloride crystals are soluble in water. When the crystals are dissolved in water (H2O), the ammonium chloride compound decomposes into its component ions: NH4+ and Cl-. The dissociation chemical reaction is:

  NH4Cl(solid) = NH4+(aqueous) + Cl-(aqueous).

  NH4+(aqueous) +H2O(liquid) = NH3(aqueous) +H3O+(aqueous)

  H3O+ +OH- = 2H2O. This particular reaction of water molecules is reversible as such H2O molecules dissociate to form H3O+ and OH- and associate to form H2O molecules.

  The ammonium chloride goes back to its solid form by crystallization.

Acidic Component

• The acidic or the basic components of ammonium chloride can be determined only at its aqueous form by dissolving the compound with water. The acidic component is the one that produces hydrogen (H+) ions when dissolved in water. Cl- is the acidic component of ammonium chloride.

  NH4Cl + H2O = NH4+ + HCl ( equation 1)

  Cl- + H2O = H+ Cl- +H2O ( equation 2)

  The chloride (Cl-) first associates with water( H2O) to form hydrochloric acid (HCl) and the dissociation of HCl produces hydrogen ions (H+).

Basic Component

• A basic component is the one that produces hydroxide (OH-) ions when dissolved in water. In aqueous solution of ammonium chloride, ammonium ions (NH4+) first associate with H2O and form ammonia and hydroxide ions.

  NH4+ + H2O = NH3 + OH- (equation 3)

  Since ammonium ions produce hydroxide ions, NH4+ are considered to be the basic components.

Acidic Nature and Uses

• The slightly acidic nature of ammonium chloride is due to the formation of hydrochloric acid (HCl), because HCl is a strong acid and its effect is dominant. Determine the acidic or basic nature by using a pH meter.

  Ammonium chloride is used as a fertilizer for growing crops like corn, wheat, barely and rice due to its higher ammonia content. It is also used in snow treatment on ski slopes at temperatures above zero degrees Celsius or 32 degrees Fahrenheit to harden snow.