Phase Diagrams

Phase Diagrams

  1. Define triple point and critical point.

  2. Demonstrate how to extract valuable information from a phase diagram.

This packet should help a learner seeking to understand how to graphically represent phase changes.

See More
Try a College Course Free

Sophia’s self-paced online courses are a great way to save time and money as you earn credits eligible for transfer to over 2,000 colleges and universities.*

Begin Free Trial
No credit card required

28 Sophia partners guarantee credit transfer.

264 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 22 of Sophia’s online courses. More than 2,000 colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.


How to Interpret a Phase Diagram

Source: Jennifer Roushar; Images from http://www.kentchemistry.com/links/Matter/Phasediagram.htm

What Does Triple Point and Critical Point Mean?

On a phase diagram, you will see the labels triple point and critical point.  The triple point is the point where all three states of matter (solid, liquid, and gas) can be found together.  Only at this temperature and pressure will you find all 3 states. 


The critical point represents the temperature at which if exceeded the substance will always be a gas no matter what the pressure is.