Question

Can an endergonic reaction be transform into an exergonic one by change of temperature? (If yes, how?)

Answer 1

It can, but doesn't have to. The general form for gibbs' energy is:
\[\Delta G = \Delta H - T \Delta \S\] If DG is positive, the rxn is endergonic. If DH is positive, and DS is positive, then the reaction has the potential to switch. As long as DH is large and positive, the rxn will be endergonic. But at T increases, DS becomes larger and more negative. As TDS begins to "catch" DH, the DG gets smaller and smaller. Eventually, we'll reach a temp such that
\[\Delta G = \Delta H - T \Delta \S = 0\]
If T gets any larger, TDS will be larger than DH, and DG will go negative, and the reaction will become exergonic.

A practical example of this is water. At RT (293K) water doesn't boil spontaneously. Once the temp increases to 373K, the reaction becomes spontaneous.

Answer 2

Thank you! It's compensate between enthalpy and entropy! Thank you for remind.

Answer 3

so we can say if DH >0 and DS >0, the reaction has a tendency to switch, however, if DH can overcome the negative TDS then the reaction will be endergonic. Right!?

Answer 4

True.

Answer 5

thank you very much.