How can I find vapour properties of a compound molten salt?

I'm carrying out thermal-hydraulic simulations of the [Aircraft Reactor Experiment](https://en.wikipedia.org/wiki/Aircraft_Reactor_Experiment) (a nuclear molten salt reactor) based on circulating **molten fuel salt**: NaF 53 mol%, ZrF4 41 mol%, UF4 6 mol%.


While the **liquid** salt thermodynamic **properties** have been measured and are hence **available**, the properties at **saturation** and the properties of the **vapour** phase are **unknown**. Due to numerical needs, I now need to switch from a *pure liquid* simulation to a "fake" *liquid + vapour* simulation ("fake" as the operating conditions should be well below the saturation temperature).


Hence, I need to introduce sensible (but not necessarily precise) thermodynamic properties for the vapour phase, as well, so that the **simulation** effectively remains in **pure liquid**.


I have all the **liquid** laws needed, for the following properties:


* specific enthalpy $h\_l(p,T) = (34.5 + 0.235 \times (T-273.15) )\times4184.$
* density $\rho\_l(p,T) = ((3.98 - 0.00093(T-273.15))\times1000.)\times\exp(10^{-9}p)$
* specific isobaric heat capacity $c\_{p,l}(p,h)$ (simply $=\dfrac{\partial h\_l}{\partial T}$)
* thermal conductivity, dynamic viscosity.


Now, similarly, for the **vapour** phase I need:


* specific enthalpy $h\_v(p,T)$
* density $\rho\_v(p,T)$
* specific isobaric heat capacity $c\_{p,v}(P)$ (which however could also be taken as the derivative of the enthalpy?)
* [thermal conductivity and dynamic viscosity, but these are less relevant for the simulation]


Whereas at **saturation** I need the following:


* pressure at saturation temperature $P(T\_{sat})$
* temperature at saturation pressure $T(P\_{sat})$
* liquid and vapour specific enthalpies at saturation pressure $h\_{l,sat}(P\_{sat})$, $h\_{v,sat}(P\_{sat})$
* similarly, liquid and vapour densities and isobaric heat capacities $\rho\_l(P\_{sat})$, $\rho\_v(P\_{sat})$, $c\_{p,l}(P\_{sat})$, $c\_{p,v}(P\_{sat})$


Since reasonably, we should be able to deduce the properties at saturation from the properties of the two phases, this makes the vapour properties the real goal.


I've started looking [here](https://webbook.nist.gov/chemistry/) for the vapour laws. For instance, I've found properties for a single component of the salt like NaF [here](https://webbook.nist.gov/cgi/inchi?ID=C7681494&Mask=1#Thermo-Gas), but I am unsure whether the properties of single molecules suit the compound salt.


So, finally: what should I do?


