LESSON 7
JUST
A PHASE
A solid has a definite volume and, if a
force is not applied to it, definite shape.
The particles in a solid are closely packed and vibrate in relation to
one another.
A liquid has definite volume, but no
definite shape. If placed in a
container in conditions other than microgravity, a liquid takes on the shape of
the container. The particles in a liquid
have more kinetic energy than those in a solid and can change position relative
to one another.
A gas has no definite shape or volume. Its particles have enough kinetic energy to
move to all parts of a container.
A fourth phase of matter, plasma, exists at
high temperatures (such as those found in stars) and consists of ionized atoms
(nuclei separated from their electrons).
As with most classification systems, some substances do not fit neatly
into these categories.
Example:
Some scientists also consider colloids to be a phase or state of matter.
Phase changes take place when molecules lose kinetic
energy and come closer together. 
Example:
Gases to liquids to solids.
Phase changes are dependent on temperature and pressure. Initiating a phase change may require a change in both temperature and pressure.
Example:
Oxygen must be compressed at a temperature less than –118 degree Celsius
before it can be liquefied.
Freezing for Celsius is 0 degrees and boiling for Celsius is 110 degrees.
For an object to raise in temperature it must
absorb heat energy.
Specific heat capacity is the amount it
needs to absorb to raise its temperature by a specific number of degrees.
Latent heat: for an object to
change state when heated, additional heat energy is required.
Latent heat of fusion: is
the heat absorbed when a solid turns into a liquid.
Latent heat of vaporization:
is the heat absorbed when a liquid turns into a gas.
Melting:
changing from a solid to a liquid
Freezing: changing from a liquid
to a solid 
Boiling: changing from a liquid
to a gas at a substances boiling point (also called vaporization)
Condensing: changing from a gas to
a liquid
