November 08, 2015
PHASE CHANGES
A phase change is a physical change.
A physical change is one in which the
physical properties of a substance are altered
but the substance remains the same kind of
matter. Phase changes in matter are melting,
freezing, vaporization, condensation, and
sublimation. (evaporation)
Indications of a chemical change are:
1. A precipitate is formed.
•
A
NEW
solid, liquid or gas will be produced that was not there
before. This is not a phase change. Could see bubbles (gas), A
solid or liquid could settle out.
2. Heat is produced or removed.
•
The temperature will increase or decrease
3. Color change.
•
An
UNEXPECTED change in color or the substance.
4. Light is produced.
•
Item glows or is giving off light.
The appearance of only one of the items may or may not indicate
a chemical change. Usually you would observe more than one to
be sure a chemical change has taken place.
