The heat of reaction for the reaction of ammonia (NH₃) and hydrochloric acid (HCl) to form ammonium chloride (NH₄Cl) is -176.2 kJ/mol. This reaction is highly exothermic, meaning it releases heat to the surroundings.

Here's why:

* Exothermic Reaction: The reaction between ammonia and hydrochloric acid is an acid-base reaction, forming a salt and water. This type of reaction typically releases heat.

* Enthalpy Change: The negative sign of the heat of reaction (-176.2 kJ/mol) indicates that the reaction releases heat, making it exothermic.

Important Notes:

* Standard Conditions: This value is typically measured under standard conditions (298 K and 1 atm pressure).

* Heat of Formation: The heat of reaction can also be calculated using the standard heats of formation of the reactants and products:

* ΔH°(reaction) = Σ ΔH°f(products) - Σ ΔH°f(reactants)

Let me know if you'd like to explore the calculation in more detail!