The heat of reaction is 180 kJ/mol hence the reaction is endothermic.
<h3>What is bond energy?</h3>
Bond energy is the energy that is required to form a bond and must be supplied in order to break the bond. In the question, we are told that the energy of the reactants is 860 kJ/mol and the bond energy of the products is 680 kJ/mol.
Heat of reaction = Bond energy of reactants - Bond energy of products
= 860 kJ/mol - 680 kJ/mol = 180 kJ/mol hence the reaction is endothermic.
