If a chemical reaction is exothermic, why is its reverse reaction always endothermic, and vice versa? (1 Viewer)

[jssicachoi]

Could i please get a sufficient answer for a 4 mark explain question please

 

[Life'sHard]

Could i please get a sufficient answer for a 4 mark explain question please

Think about it. If you're losing energy on the way out, in order to return back to the original state, you need to regain that energy that was lossed. And hence why in this situation, the forward is exo and the reverse is endo.

 

[jssicachoi]

Think about it. If you're losing energy on the way out, in order to return back to the original state, you need to regain that energy that was lossed. And hence why in this situation, the forward is exo and the reverse is endo.

is there are way you can construct an explanation as if you were answering a question in an exam, with terms such as activation energy?

 

[Eagle Mum]

All molecules exist with a specific level of potential energy (the two dotted horizontal lines in the diagram). The fixed difference between the sums (levels) of the potential energy of the reactants vs the products determines if the reaction is exothermic or endothermic but like a landscape, the level of the plain/valleys on either side of a hill are fixed and so is the magnitude of the difference (ΔG), with the direction of the reaction determining if it is exothermic or endothermic (down or up - in graph diagram, also left or right).
Diagram from Khan Academy
The hill in between represents the potential energy of a transitional state through which the reactant molecules have to pass (by binding together) before reaching the products’ state. The activation energy (EA) is the amount of energy required to go from the combined energy level of the reactants to that of the transition state. An enzyme is like finding an alternative route over the hill (different transition shape as the enzyme enables reactants to bind differently).