Answer:
The balanced chemical equation represents the reaction between phosphorus pentachloride (PCl5) and heat, which produces phosphorus trichloride (PCl3) and chlorine gas (Cl2):
PCl5 + heat → PCl3 + Cl2
Interpreting the equation in terms of the relative number of moles, we can see that 1 mole of PCl5 reacts to produce 1 mole of PCl3 and 1 mole of Cl2.
The given equation is exothermic because it releases heat (92.9 kJ) as a product. This can be seen by the positive sign of the heat term in the equation.