3. Phase Diagram Vocabulary
Triple Point: Only point at which all three phases (solid, liquid, gas) exist at equilibrium
Critical Point: Point at which no amount of pressure can turn a gas into a liquid.
Phase Boundries: Line along which 2 phases exist at equilibrium.

4. Phase Diagram Vocabulary
Standard Melting Point: Temperature at which a substance exists in solid/liquid equilibrium when at (1 atm) standard pressure
Standard Boiling Point: Temperature at which a substance exists in liquid/gas equilibrium when at (1 atm) standard pressure
Not all substances have standard boiling and melting points.