Answer:
The chemical reaction you provided is:
H-H + Cl-Cl → 2H-Cl
To calculate the enthalpy change of this reaction, you need to know the enthalpy of formation for each of the species involved.
Assuming standard conditions (25°C and 1 atm pressure), the enthalpy change of this reaction can be calculated using the following equation:
ΔH° = ΣnΔH°f(products) - ΣmΔH°f(reactants)
where ΔH° is the enthalpy change under standard conditions, n and m are the stoichiometric coefficients of the products and reactants, respectively, and ΔH°f is the standard enthalpy of formation of the species.
Using the standard enthalpy of formation values from the NIST Chemistry WebBook, we can calculate the enthalpy change of the reaction as follows:
ΔH° = [2(-92.31 kJ/mol)] - [1(436.47 kJ/mol) + 1(103.63 kJ/mol)]
= -242.58 kJ/mol
Therefore, the enthalpy change of the reaction is -242.58 kJ/mol, which indicates that the reaction is exothermic and releases heat to the surroundings.