# Changes in entropy and Gibbs free energy for sublimation at triple point [closed]

The standard enthalpy of sublimation of dry ice (solid carbon dioxide) is $$\Delta H=6.03\ \mathrm{kJ/mol}$$. The triple point of $$\ce{CO2}$$ is at $$p=5.1\ \mathrm{atm}$$, $$T=-56.7\ \mathrm{^\circ C}$$.

I am trying to find the $$\Delta S_\text{sublimation}$$ and $$\Delta G_\text{sublimation}$$ at the triple point. I do not know which formula to use.

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$$\Delta_\mathrm{sub} G = 0$$
$$\Delta_\mathrm{sub} S_\mathrm{m} = \frac{\Delta_\mathrm{sub} H_\mathrm{m}}{T_\mathrm{sub}}$$
Note however that the value of $$\Delta_\mathrm{sub} H_\mathrm{m}$$ that you provide seems a bit off$$^\dagger$$. NIST gives a value at $$\pu{207 K}$$ of $$\Delta_\mathrm{sub} H_\mathrm{m} = \pu{26.1 kJmol^{-1}}$$. Values at other temperatures in the range $$\pu{167-195 K}$$ are similar. Other internet sources can helpfully confirm this.
$$\dagger$$ The value you post may be in $$\pu{kcal mol-1}$$, then it would translate into $$\pu{25.3 kJ mol-1}$$, in reasonable agreement with the values on the NIST data page.