* Breaking Bonds: When NH₄Cl dissolves, the ionic bonds between NH₄⁺ and Cl⁻ ions are broken, requiring energy input.
* Hydration: The ions then become surrounded by water molecules (hydration), which releases energy.
* Net Energy Change: In the case of NH₄Cl, the energy required to break the ionic bonds is greater than the energy released during hydration. This means the overall process absorbs energy from the surroundings, making it endothermic.
Evidence:
* Cooling Effect: You can observe this endothermic nature by feeling the beaker containing the dissolving ammonium chloride. The solution will feel colder because it's absorbing heat from the surroundings.
* Enthalpy Change: The enthalpy change (ΔH) for dissolving NH₄Cl is positive, which is a characteristic of endothermic reactions.
So, why might someone think it's exothermic?
It's possible that the confusion arises from observing the rapid dissolving of NH₄Cl. This rapid dissolving might give the impression of heat being released, but it's actually the result of the endothermic process drawing heat from the surroundings.
