Separation of Mixtures: Properties in Matter
E.Y. Siu and B. L. Fireng
1. Introduction:
In developing sensing devices, a selective medium is usually employed to collect the
compound(s) of interest and ease detection. To achieve selectivity, compound(s) of interest must
be differentiated from other contaminants. One differentiation mechanism is to make use of the
physical properties of the mixture.
In the following lesson, students will observe separation of mixtures. Separation will occur
based upon differences in physical properties. Two different mixtures are proposed for variation
in the depth of content coverage desired and the materials available.
The proposed lesson plan addresses the physical science strands and is intended for 8th grade.
2. Standards:
Arizona Grade 8
Strand 5: Physical Science
Concept 1: Properties and Change of Properties in Matter
PO 1. Identify different kinds of matter based on the following physical
properties:
 States
 Boiling point
 Solubility
PO 5. Classify mixtures as being homogenous or heterogeneous
PO 7. Investigate how the transfer of energy can affect the physical and
chemical properties of matter
3. Lesson Description:
Mixture No. 1
Materials:
 5 grams of sand
 5 grams of salt
 5 grams of iron filings
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5 grams of wood chips
Bottle of water
Magnets
Tweezers
Pipettes
Coffee filters
Paper towels
Beakers
Hot plates
Thermometer
Magnifying glass
Computer
Test tubes
Funnels
Personal Protective Equipments / Precautions:
 Lab Coats
 Goggles
 Heat Gloves
* Be sure to tie back long hair.
Procedures:
1. Provide students with the mixture
2. Allow student (in groups) some time to make observations
3. Have a class discussion on the observations and the things they noticed and know
about the individual components can be use for separation
4. Have students generate hypothesis (in groups) on how the mixtures can be separated
based on their observations and the discussion
5. (The iron filings can be separated with a magnet. The wood chips can be separated
by adding water to the water and picking the floating wood chips from the top. The
sand can be separated by pouring the water/sand/salt mixture through a coffee filter or
a paper towel. The remaining water and salt can be collected in a beaker and heated
on a hot plate until all of the water evaporates.)
6. Provide materials for students to test out their hypothesis
7. Have student reflect on their separation plan
8. Conclude lesson with a discussion of what happened and label terms if necessary
9. Discuss benefits of separation (and how separation relates to detection)
Mixture No. 2
Materials:
 20mL of water
 20mL of acetone
 20mL of ethanol
 5 grams of sand
 5 grams of salt
 Tweezers
 Hot plates with accurate temperature control
 Pipettes
 Coffee filters
 Thermometer
 Magnifying glass
 Computer
 Paper towel
 Beakers
 Test tubes
 Funnels
Personal Protective Equipments / Precautions:
 Lab Coats
 Goggles
 Heat Gloves
 Chemical fume hoods
* Be sure to tie back long hair.
Procedures:
1. Provide student with a “real-world” scenario (example given below)
Example Scenario: You are all chemists/engineers who live in the same town and
work for the same company. A river runs through your town and the water comes
from three smaller rivers that pass through three big cities. Recently, your town ran
out of drinking water and your non-chemist, non-engineer neighbors have been
drinking the water from the river. A few days later, many of your neighbors started
feeling sick. You suspected the river water and half of you went to City No. 1 and the
other half went to City No. 2 to see what is in their river. In City No. 1, you saw that
a factory is right next to the river and they have been putting chemicals in the river.
In City No. 2, the other half of you saw that the water appears to be clean but have a
lot of sand in it. You are now asked to come up with a way to separate the chemicals
from the water in City No. 1 and the sand from the water in City No. 2.
2. Pre-assessment: Have students spend 5 minutes discussing ways to separate the
components from the water in their groups
3. Have students share with the class what they came up with
4. Demonstrate separation of a binary water / acetone mixture by heating the mixture
above acetone’s boiling point and below 100°C
5. Have students make observations and discuss what they think happened
6. Discuss how by noting the temperature (boiling point) at which the chemical became
a gas, we can determine what chemical was in the water
7. Optional: Discuss other 8th grade science concepts (i.e. the changes in states from
liquid to gas during heating, boiling point of acetone versus boiling of water, mixture
classification, transfer of heat energy, physical changes versus chemical changes)
8. Continue to scenario to identify components in the mixture (continuation of example
given below)
Example Scenario (continued): A separate group of chemists/engineers went to City
No. 3 and found that ethanol and salt are in their river water. That means a mixture of
water, ethanol (isopropanol), acetone, salt, and sand is in the river that runs through
your town. Remember, your town is out of drinking water, so you must clean the
river water and separate all the chemicals, salt, and sand from the river water to have
drinking water!!!
9. Provide students with a mixture of water, ethanol or isopropanol, acetone, salt, and
sand
10. Allow student (in groups) some time to make observations and research on the
internet about the different components
11. Have students generate hypothesis (in groups) on how the mixtures can be separated
based on the principles from the demonstration and the brief discussion on separation
by differences in boiling point
12. (The sand can be separation by using filters, i.e. coffee filters, paper towel. The salt
will dissolve in the mixture. As the mixture is heated, acetone will vaporize,
followed by ethanol or isopropanol. Lastly, water can be boiled off or let stand to
vaporize to obtain salt crystals.)
13. Provide materials for students to test out their hypothesis
14. Have student reflect on their separation plan
15. Conclude lesson with a discussion of what happened and label terms if necessary
16. Discuss benefits of separation (and how separation relates to detection)
4. Assessment:
Have students propose separation technique for a different mixture (i.e. Love Canal scenario)