 Okay, so here's your task for this video. I've drawn an energy diagram here and I've put it on an actual numbered scale, so we've got some values for our enthalpies. First I'd like you to work out what's the value of delta H, the enthalpy change, for this reaction. And then I'd like you to work out what's the value of the activation energy. Then tell me whether it's an exothermic or an endothermic reaction. And then finally imagine that you could run the reaction in reverse, so you're starting at the products and you're going back to the reactants. What can you say in this case about the energy changes for that reverse reaction? Okay, that's the end of section one.