Editing Raoult's law (section)

===Non-ideal mixing===
In elementary applications, Raoult's law is generally valid when the liquid phase is either nearly pure or a mixture of similar substances.<ref>{{cite book |last1=Felder |first1=Richard M. |last2=Rousseau |first2=Ronald W. |last3=Bullard |first3=Lisa G.|date= 2004-12-15|title=Elementary Principles of Chemical Processes |publisher=Wiley |page=293 |isbn=978-0471687573 }}</ref> Raoult's law may be adapted to non-ideal solutions by incorporating two factors that account for the interactions between molecules of different substances.  The first factor is a correction for gas non-ideality, or deviations from the [[ideal-gas law]]. It is called the [[fugacity coefficient]] (<math>\phi_{p,i}</math>). The second, the [[activity coefficient]] <math>\gamma_i</math>, is a correction for interactions in the liquid phase between the different molecules.<ref name = K-CChao />{{rp|326}}

This modified or extended Raoult's law is then written as<ref name = "Che Thermo">
{{Citation
  | last1 = Smith| first1 = J. M.
  | last2 = Van Ness| first2 = H. C.
  | last3 = Abbott| first3 = M. M.
  | title = Introduction to Chemical Engineering Thermodynamics
  | place = New York
  | publisher = McGraw-Hill
  | year = 2005
  | pages = 545
  | edition = seventh
  | isbn = 0-07-310445-0}}
</ref>
: <math>y_i \phi_{p,i} p = x_i \gamma_i p_i^\star.</math>