How does heat capacity relate (mathematically) to density? I imagine first relating entropy to density, it will depend on the molecular structure and everything, but is there a general formula ? http://en.wikipedia.org/wiki/Volumetric_heat_capacity I found this link, and it deals with Volumetric Heat Capacity. It is not exactly what I'm looking for. Can one make the assumption that decrease in density leads to increase in degrees of freedom, entropy?