1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A question about terminology of phase state & criticality

  1. Jul 8, 2012 #1
    I'm looking at the diagram (Figure 1) at


    I get that the region in which both the temperature & pressure are higher than the critical point is called a supercritical fluid, which really means it is both a gas & a liquid, thermodynamically speaking.

    And as I understand it, the term subcritical gas or liquid is for the region in which the temperature & pressure are both less than the critical point - with the subcritical gas also termed a vapor here.

    But what about a gas that is a higher temperature but lower pressure, or a liquid at a higher pressure, but lower temperature, than the critical point. It seems that there should be some term for this that is something like a "saddle" state. I don't think the term supercritical should be used, but something with critical should be.

    Any idea what the terminology of this is?
  2. jcsd
  3. Jul 10, 2012 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Isn't it just normal gas? How does it differ?

    Isn't it just a normal liquid? Ditto?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook