On the reaction profile for a reaction, the reactants are at 250 kJ mol−1250\,\mathrm{kJ\,mol^{-1}}250kJmol−1, the top of the energy barrier is at 400 kJ mol−1400\,\mathrm{kJ\,mol^{-1}}400kJmol−1 and the products are at 130 kJ mol−1130\,\mathrm{kJ\,mol^{-1}}130kJmol−1.
A catalyst lowers the top of the energy barrier to 310 kJ mol−1310\,\mathrm{kJ\,mol^{-1}}310kJmol−1.
Which row gives the activation energy and the overall energy change for the catalysed reaction?
activation energy 60 kJ mol−160\,\mathrm{kJ\,mol^{-1}}60kJmol−1; overall change −120 kJ mol−1-120\,\mathrm{kJ\,mol^{-1}}−120kJmol−1
activation energy 180 kJ mol−1180\,\mathrm{kJ\,mol^{-1}}180kJmol−1; overall change −120 kJ mol−1-120\,\mathrm{kJ\,mol^{-1}}−120kJmol−1
activation energy 90 kJ mol−190\,\mathrm{kJ\,mol^{-1}}90kJmol−1; overall change −120 kJ mol−1-120\,\mathrm{kJ\,mol^{-1}}−120kJmol−1
activation energy 60 kJ mol−160\,\mathrm{kJ\,mol^{-1}}60kJmol−1; overall change +120 kJ mol−1+120\,\mathrm{kJ\,mol^{-1}}+120kJmol−1
53 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.