Phase Diagrams

The phase of a subtance (solid, liquid, gas) depends on its temperature and pressure.

phase diagram: a graph showing the phase(s) present at different temperatures and pressures.

fusion curve: the set of temperatures and pressures at which a substance melts/freezes. (Curve AD on the graph)

vaporization curve: the set of temperatures & pressures at which a substance vaporizes/condenses. (Curve AB on the graph.)

sublimation curve: the set of temperatures & pressures at which a substance sublimes/deposits. (Curve AC on the graph.)

triple point: the one temperature and pressure at which a substance can exist simultaneously as a solid, liquid, and gas. (Point A on the graph.)

critical point: the point on the vaporization curve that corresponds to the highest temperature at which the substance can exist as a liquid. (Point B on the graph.)

Phase Diagram for H₂O