An endothermic reaction was found to have an activation energy of 100 kJ. If this reaction is reversed, the activation energy is only 20 kJ. What is the value of delta H for the endothermic reaction?

Answer 1

For an endothermic reaction, Ea forward = Ea reverse + delta E rxn.

Answer 2

So the answer would be positive 120 kJ?

Answer 3

No. If Ea forward is 100 and Ea reverse is 20, then delta E reaction is 80.

Answer 4

I looked for and count not find a good diagram. Finally I succeeded.
http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm
You can see that 40 + 30 = total = 70 for exothermic and equally you see that 100 = total = 20 + 80
http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm