When H2(g) reacts with Cl2(g) to form HCl(g) , 185 kJ of energy are evolved for each mole of H2(g) that reacts. Write a balanced thermochemical equation for the reaction with an energy term in kJ as part of the equation. Note that the answer box for the energy term is case sensitive. Use the SMALLEST INTEGER coefficients possible and put the energy term (including the units) in the last box on the appropriate side of the equation. If a box is not needed, leave it blank.

In a chemical reaction, enthalpy of reaction ΔH is a thermodynamic constant that gives information if the reaction is exothermic (Produce heat if reacts) or endothermic (Consume heat if reacts).

In the reaction:

H₂(g) + Cl₂(g) → 2HCl(g) ΔH = -185kJ

As ΔH <0, the reaction is exothermic, that means, produce heat, writing a balanced thermochemical equation:

H₂(g) + Cl₂(g) → 2HCl(g) + 185kJ

The enthalpy is as a product beacause an exothermic reaction produces heat.

I hope it helps!