[sasan_f3000]

Where is the activation energy when we have a potential energy diagram with 2 bumps. Like it starts at 100 KJ, then goes up to 130 KJ, then back down to 120 KJ, Up again to 140 KJ then down to 135 KJ. This is an endothermic reaction but I don't know where the activation energy is. Is it from 140 KJ to 100 KJ?

[nj_bartel]

That is a two step reaction, so there are two separate activation energies - one for each step, from the reactants to the transition state.