Skip to main content
1 of 2
Mäßige
  • 471
  • 1
  • 4
  • 16

Favorability of a reaction with positive entropy change and negative enthalpy change

Suppose a reaction had a positve entropy change and a negative enthalpy change.

According to Le Chatelier's principle, the reaction should be less favorable at higher temperatures, as heat is released. The same is applicable when looking at a Van't Hoff plot:

enter image description here

However, the entropy change is also positive, and as

$\Delta G=\Delta H-T\Delta S$

one would expect the gibbs energy to decrease at higher temperatures, therefore increasing the reaction's equilibrium constant:

$K=e^{\frac{-G^{0}}{RT}}$

So what is going on here, why do those two statements contracdict?

Mäßige
  • 471
  • 1
  • 4
  • 16