A user today wrote $G^0$ (G^0) to indicate standard Gibbs energy. I quickly edited it to $G^\circ$ (G^\circ) instead as that's the notation I'm used to more.

However, then I realized an intriguing fact. Whenever I speak $G^\circ$ (in English at least) I say it as "G naught". I don't call it "G circle" or "G not" instead. The word "naught" in English means "nill", "nothing", or, well, "zero"!

Thus, based on its mode of speaking, it makes more sense to write G^0 than G^\circ.

This has not been covered before so I am asking it now. I checked the green book but couldn't find "Latex depiction of thermodynamics symbols" or any related topic.

What is the standard LaTeX depiction of G^0? And sister symbols like E^0...?


The standard state is indicated by the standard state sign (not available in standard LaTeX), or a circle, as recommended in Green Book 2.11.1 (ii) p.60:

Green book 2.11.1 (ii) p.60 (screenshot)

It is definitely not a zero, naught, nill, oh, ... . In absence of any of these symbols, one should resort to specifying parameters in parentheses ($G(\pu{273.15 K})$), or for what it's worth, $G(\text{std.})$ might be acceptable, too.

I personally have neither used nor heard the term G "naught", to me precise language matters, ergo: standard Gibbs energy/ standard free energy.

  • $\begingroup$ "I personally have neither used nor heard the term G "naught"" Intriguing! So, if you were to speak the equation $\Delta G^\circ=-RT\ln K$ aloud, would you read "delta standard G" or "delta G naught"? Am asking because in our class we always did the latter :P $\endgroup$ Feb 27 '18 at 13:10
  • 2
    $\begingroup$ @GaurangTandon when we're all looking at the same page: Delta G is sufficient I think, otherwise: Delta G (at) standard (conditions), in written form: just the symbol, or the energy difference in the standard free energy. $\endgroup$ Feb 27 '18 at 14:06

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