Subject: HEAT OF FORMATION VS> FREE ENERGY

From: "E. Lewars" <[email-masked]>
Date: Thu, 31 Dec 1998 15:21:13 -0500 (EST)

1998 Dec 31, Thursday

     HEATS OF FORMATION AND FREE ENERGIES

 There are extensive tabulations (whole books) of heats of formation (enthalpies
of formation), and many papers in the literature on ways of calculatig them.
Semiempirical methods like AM1 and PM3 are designed to give useful heats of
formation. And obviously differences in heats of formation provide an indication
of the thermodynamic stability of a compound:
        deltaH(products) - deltaH(reactant)

Question:
 What about free energies? Aren't these _more_ important, since it is
deltaG, not just deltaH, that determines thermodynamic stability? Why doesn't
free energt get as much attention in tables and papers as enthalpy?

  Thanks

  Happy new year

  E. Lewars
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