1. Heating Curves
Phase changes & Energy

2. Phase Changes
All phase changes occur at a constant temperature and have a constant kinetic energy
To get to a phase change
Heat added = increasing the movement of the particles = increasing the kinetic energy
Heat released = decreasing the movement of the particles = decreasing the kinetic energy
These changes in kinetic energy allow the molecules/atoms to move apart (increasing energy) or come together (decreasing energy)

3. Types of Phase Changes
Fusion (melting): phase change from a solid to a liquid
Boiling (vaporization): phase change from a liquid to a gas
Sublimation: phase change from a solid to a gas
Solidification (freezing): phase change from a liquid to a solid
Condensation: phase change from a gas to a liquid
Deposition: phase change from a gas to a solid
Which 3 phase changes are exothermic? Which 3 are endothermic?

4. Heating Curves
Heating curves: graphically describe the energy changes that take place during phase changes
Show the temperature of each phase change
Show the boiling and melting points of a substance
Can be used to determine the phase of matter of a substance at a given temperature

5. Heating Curves and Phase Changes
All heating curves have the same general shape
Diagonal – flat line – diagonal – flat line – diagonal
The flat lines represent the phase changes
The temperatures for the flat lines represent the melting and boiling points for the substance
Kinetic energy and temperature are constant while potential energy is changing
There are two phases of matter present
The diagonal lines represent a change in kinetic energy and temperature
There is only one phase of matter present
What is the melting point for this substance? The boiling point?

6. Copy this heating curve into your notes and label the following
Particle diagrams at the top
Phase changes at each letter
What phase changes are occurring at each letter
The melting and boiling point for this substance E D C B A