In a reaction, breaking the bonds in the reactants needs 2648 kJ mol−12648\,\mathrm{kJ\,mol^{-1}}2648kJmol−1 and making the bonds in the products releases 2553 kJ mol−12553\,\mathrm{kJ\,mol^{-1}}2553kJmol−1. Which statement is correct?
ΔH=−95 kJ mol−1\Delta H=-95\,\mathrm{kJ\,mol^{-1}}ΔH=−95kJmol−1, so the reaction is exothermic
ΔH=+95 kJ mol−1\Delta H=+95\,\mathrm{kJ\,mol^{-1}}ΔH=+95kJmol−1, so the reaction is exothermic
ΔH=+95 kJ mol−1\Delta H=+95\,\mathrm{kJ\,mol^{-1}}ΔH=+95kJmol−1, so the reaction is endothermic
ΔH=−95 kJ mol−1\Delta H=-95\,\mathrm{kJ\,mol^{-1}}ΔH=−95kJmol−1, so the reaction is endothermic
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.