The document discusses key concepts related to phase changes of matter including heat of fusion which is the energy required to change a substance from a solid to a liquid, heat of vaporization which is the energy required to change a liquid to a gas, cooling curves which show phase changes from gas to solid or liquid to solid, and phase diagrams which illustrate phase boundaries including the triple point where solid, liquid, and gas phases coexist and the critical point which is the highest temperature and pressure point of a substance in its gas phase.

2. Heating curve
Heat of fusion
Is the change in its enthalpy resulting
from providing energy, typically heat,
to a specific quantity of the substance
to change it state from a solid to a
liquid, at constant pressure.
Heat of vaporization
Is the amount of energy that must be
added to a liquid substance to
transform a quantity of that
substance into a gas.

3. Cooling curve
Is a line graph that
represent the change of
phase of matter, typically
from a gas to a solid or a
liquid to a solid

4. General Phase Diagram
.
Two Points:
*Triple Point
-refers to the temperature
and pressure at which all
three phases (solid,
liquid, and gas) coexist in
a dynamic equilibrium.
*Critical Point
-refers to the critical
temperature and the
critical pressure together.