1

Are EOSs merely correlations that mathematically represent (in a better or worse way) experimental data or do they have a theoretical background? How are they developed (suppose one wishes to develop his/her own EOS -- how would he/she start and which script should he/she follow?).

Carlos Gouveia
  • 301
  • 2
  • 5
  • related http://chemistry.stackexchange.com/questions/549/what-is-a-rigorous-definition-of-gas-volume-and-how-is-the-van-der-waals-equati – Mithoron Jun 03 '16 at 20:02
  • At least some EOSes may be derived from first principle using statistical physics approach. However, originally they were developed from general considerations and trial and error. – permeakra Jun 04 '16 at 09:33

1 Answers1

2

They are merely brief and approximated ways to describe observed relations among state parameters. They do not need to have a theoretical background, but many times they have. It helps to create them and provides some reliability. The theory used to guide the construction of a EOS is anyone that turns to be useful.

how would he/she start and which script should he/she follow?

It is a very broad question. In thermodynamics there are few state parameters used normally. Thermodynamic theory is a macroscopic theory of somewhat general applicability, but EOS can be very specific, and this specificity can not be provided by thermodynamics, so, it turns to be a wide search. In cases where simple general relations exist (mostly already discovered), it can be found just by fitting a data to a function.

user1420303
  • 1,987
  • 1
  • 12
  • 19
  • 1
    Statistical thermodynamics provides the methodology for deriving the virial equation of state based on first principles. It starts out by looking at the potential energy interactions between a pair of molecules of the gas (to get the first virial coefficient). – Chet Miller Jun 04 '16 at 12:08