Activity Name: Mixtures and Solutions
Target Subject: Physical Science
Purpose: To create heterogeneous and homogeneous
mixtures and solutions, identify the differences, and to
explore the concepts of concentration and dilution.
Background Information: Mixtures contain more than
one kind of particle, (atoms, molecules, and or
compounds). A heterogeneous mixture contains
particles that are not the same, can be separated by
physical means, and are not distributed the same
throughout the mixture.Trail mix is a good example.
In homogeneous mixtures and solutions the particles are distributed
evenly throughout the mixture and are not easily separated. A
thoroughly mixed glass of lemonade is a good example. In science the
lemonade powder, or whatever is being dissolved, is referred to as a
solute. The substance doing the dissolving is called a solvent. In the
lemonade solution, water is the solvent. The amounts of solvent and
solute can be changed to create various concentrations of the solution
from dilute to concentrated, or even oversaturated, where no more
solvent will dissolve.
Preparation: Depending on the experience of the students and the
time available, this activity can be presented as three different activities
or done sequentially. Preparation involves obtaining the various
supplies listed in the materials list.
Materials:
 Trays
 Bowls
 Cups
 Ingredients for trail mix such as small candies, raisins, pretzels, etc.
 Variety of small none edible objects such as buttons
 Powdered drink mix
 Water
 Spoons or stirring rods
 Rubber gloves
Procedure:
1. If use of food is permitted in the setting, create trail mix by adding
a small amount of separate ingredients from individual containers
into one large bowl. Following a recipe for trail mix gives practice
in measuring skills.
2. Mix with gloved hands. Divide into small containers and eat
noticing the variety and numbers of items in the mixture and how
easily they are separated.
3. If food is not allowed or available, use a variety of small objects
such as buttons, bells, and pompoms. The different sizes and
textures will support the idea of heterogeneous mixtures.
4. Follow the same procedure as described above, except after the
items have been combined in one large bowl they can be
tactually re-separated back into the original containers.
5. Make a powdered drink mix with water to illustrate how a
homogeneous mixture is not easily separated.
6. While stirring with a spoon or stirring rod, note the gritty feeling of
the crystals before they dissolve. An effective stirring technique
to facilitate dissolution is stirring in a circle a few times then
stirring in a zigzag line back and forth across the container.
7. Alternate these methods until the crystal seem to disappear.
They have not vanished; they are in solution, hanging out
between the molecules of water.
8. If allowed, taste the water before the crystals are added, then
after they have dissolved, and note the differences.
9. The concepts of diluted and concentrated solutions can be
experienced by adding more or less of the solute (the powdered
drink mix).
10. Salt and water provide an easy way to show that some solutions
can be separated by evaporation. Tactually observe the crystals
dissolving. After the salt solution is left to evaporate, feel the
crystals that have reformed in the container and note that the
water has evaporated.
Safety Note: Remember lab materials should never be tasted unless
directed by instructor.