[XGen]

This may be a silly question, but how do I calculate the Ka of HF from thermodynamic values? I realize that most likely I have to be using the standard Gibbs free energy of reaction and the formula ΔG = -RT ln K, but what value of R would I use? How would I go about doing this in general?

[SinkingTako]

This may be a silly question, but how do I calculate the Ka of HF from thermodynamic values? I realize that most likely I have to be using the standard Gibbs free energy of reaction and the formula ΔG = -RT ln K, but what value of R would I use? How would I go about doing this in general?

R = 8.31447

see this:
www.chemteam.info/AcidBase/calc-Ka-from-thermodynamic-data.html

[XGen]

The question I am doing is for hydrofluoric acid, whose Gibbs free energy of formation is given to me as -296.82. This yields an answer that is very, very small. Am I doing something wrong then? I'm using R = 8.3145 and T = 298 K.

[Sophia7X]

delta G formation is for HF being formed from its elements, H2 and F2. Ka is for HF dissociation, HF  H⁺ + F^-

[XGen]

It is listed as HF(aq) if that's any difference.