2. Recall:
Describe what happened in your
activity?
What was the mixture that you
evaporated?
What substance could you collect after
the distillation process? What about
after evaporation?
Differentiate mixtures from substances.
3. Characteristics of Mixtures
may be solid, liquid or gas
may be homogeneous or
heterogeneous
made up of two or more components
components may be
separated/recovered by physical
means such as filtration, evaporation
and distillation
4. Looks can be deceiving!
For the unknown solid, determine its melting point to
identify whether it is a substance or a mixture. A
substance melts sharply, while a mixture takes longer
time to completely melt.
For the unknown liquid, determine its boiling point to
identify whether it is a substance or a mixture. A
substance has a constant boiling point, while a mixture
boils at a temperature range.
Note that the method has to be repeated at least three
times before the student can conclude if their unknown
sample is a substance or a mixture.
5. There are mixtures that are
homogeneous which may be
mistaken as substances. Being
so, appearance may not be the
best basis to differentiate
substances from mixtures.
However, there are ways to tell by
noting how a sample behaves
during boiling and melting.
6. During boiling, the temperature of
a substance changes at the start
then it does not change anymore
after; while, the temperature of a
mixture changes.
During melting, the substance
melts completely almost at the same
time while mixtures have portions
that do not melt.
7. All substances are homogeneous. Some
mixtures are also homogeneous. Being so, it is
difficult to distinguish mixtures and substances
based on appearance.
You will find out that substances may further
be classified into two: compound and
element.
How are elements different from compounds?
How are they similar?
