1. Dissolution: The ionic bonds in the ammonium chloride crystal lattice break, and the individual ions (NH₄⁺ and Cl⁻) are released into the water.
2. Hydration: The released ions become surrounded by water molecules. The positively charged ammonium ions (NH₄⁺) attract the negatively charged oxygen ends of water molecules, while the negatively charged chloride ions (Cl⁻) attract the positively charged hydrogen ends of water molecules. This process is called hydration.
3. Formation of an aqueous solution: The hydrated ions are now free to move around in the solution, forming a homogeneous mixture of ammonium and chloride ions in water.
Overall reaction:
NH₄Cl(s) + H₂O(l) → NH₄⁺(aq) + Cl⁻(aq)
Important points to note:
* The solution becomes slightly acidic due to the hydrolysis of ammonium ions (NH₄⁺). Ammonium ions can donate a proton (H⁺) to water molecules, forming hydronium ions (H₃O⁺) which make the solution acidic.
* The dissolution of ammonium chloride is an endothermic process, meaning it absorbs heat from the surroundings. This can be observed as a slight decrease in temperature of the water.
* The pH of the solution will depend on the concentration of ammonium chloride. Higher concentrations will result in a lower pH (more acidic).
Uses of ammonium chloride:
Ammonium chloride has various applications, including:
* Fertilizer: Provides nitrogen for plant growth
* Food additive: Used as a yeast nutrient and acidity regulator
* Medicine: Used in cough syrups and expectorants
* Electroplating: Used as an electrolyte
* Textile industry: Used as a mordant and in dyeing processes
