How can I draw an endergonic reaction in a potential energy diagram?

1 Answer
Truong-Son N.
Nov 20, 2015

Exergonic and endergonic qualifications only apply for Gibbs' free energy. Enthalpy applies to potential energy diagrams.

Endergonic just means that #DeltaG_"rxn" > 0#. So, the Gibbs' free energy of the products is higher than the Gibbs' free energy of the reactants.

http://www.kshitij-iitjee.com/

Now, since we do have #DeltaG > 0#, since we know that #DeltaS > 0#, #DeltaH# must be positive. Either #DeltaH# is large and positive, or the temperature is low enough such that #Delta H > TDeltaS#.

#DeltaG_"rxn" = DeltaH_"rxn" - TDeltaS_"rxn"#

So, the reaction is necessarily endothermic, and the reaction coordinate diagram and potential energy diagram look similar.

http://www.spiritsd.ca/

The main difference is again, you'd be using #DeltaH_"rxn"# instead, and your y-axis would be the potential energy, NOT the Gibbs' free energy.

Related questions
See all questions in Potential Energy Diagrams
Impact of this question
13232 views around the world
You can reuse this answer
Creative Commons License