Sorry but could you explain again the purpose of the rate limiting step? (If we want to affect the whole reaction sequence, we can do it most efficiently by affecting the rate limiting step, which is useful for the synthetic design. - GS). I know it takes up the most energy (compared to the other steps in the reaction) and that we determine it from the largest distance from the minima to maxima but I am unclear as what the relevance is? Thanks (The larger that distance, the more difficult it is for the reaction to jump over that “hill”, so the reaction is slower. - GS). Which way was which? If the starting energies are lower than the final states, then it produces heat? or vice versa? (No, you need to supply the missing energy by heat - GS).

Also how can we tell if a reaction is absorbing heat or producing heat from the reaction coordinate diagram? (By comparing energies of the initial and final states. - GS).