January 24th, 2014
Kellen McDonnell
Page 1
Mystery Mixture
Teacher’s Instructions
Description: In this activity, students will use the characteristics of substances to find tests to
separate the substances in a vial and determine what they are.
Learning Goals:
Learn the difference between homogeneous and heterogeneous mixtures
Learn to use characteristics of substances to identify them
Use physical characteristics to separate a mixture.
Recommended Grades:
3-8
Estimated Time Required:
45-60 minutes
Key Concepts and Terms:
Homogeneous – uniform throughout
Heterogeneous – unevenly distributed
Solution – a homogeneous mixture with one or more substances dissolved in another
What happens and why:
All of the different components of the mystery mixture have different properties, baby
oil is less dense than water, steel wool is attracted to magnets and pepper isn’t, salt is
crystalline and has a higher boiling point than water, etc. These allow different tests to isolate
the different components.
Materials Needed:
Per Student or Group:
1 mystery vial
-4 mL of water
-3 mL of Baby oil
-1 gram of salt (NaCl)
-1 gram of pepper
-1 gram of steel wool clippings
1 taxonomy flow chart
Per class:
Pipet Station:
Pipets
Cups to transfer oil into
Kellen McDonnell
January 24th, 2014
Page 2
Filtration station:
Small glass beakers
Plastic funnels
Coffee filters
Popsicle sticks
Magnets
Magnifying glasses
Boiling Station:
Hot plate
Safety Information:
Glassware is breakable
General Outline:
1. Mention how scientists use a variety of techniques to separate mixtures and
identify unknown substances. Describe the stations set up and how to use the
taxonomy flow chart.
2. Pass out one vial and one flow chart per group.
3. Set the students loose, while providing assistance as needed at each station.
4. When students have completed all of the tests and identified all of the substances
correctly, talk about the importance of using different techniques for different
substances. Mention homogeneous and heterogeneous substances and ask the
students what different mixtures are.
5. Clean up by disposing of liquids and solids and rinsing all glassware.
Kellen McDonnell
January 24th, 2014
Page 3
Mystery Mixture Teacher Kit
Student Instructions
Directions:
1. Observe the mixture in the vial. What do you see?
2. Mass the vial.
Mass = _____________________
3. The goal is to separate the mixture into each of its individual components. There are
several stations set up with different techniques and it is your job to determine what to
use to isolate each ingredient.
4. At the end, you will want to be able to mass all of your ingredients to know of exactly
what the mixture was composed.
5. Use the taxonomical flow chart to identify each ingredient.
Kellen McDonnell
January 24th, 2014
Page 4
Notes:
The substance chart attached is for the experiment I did in the lab in which students
used 5 tests to collect data about unknown substances and then used the same
tests on known substances to determine the identity of the mystery substances.
This is best done with more supervision than explicitly stated in the instructions.
The experiment is good for 5th grade and up (lots of data collecting and independent
thought)
By using more complicated tests for characteristics such as pH or chemical reactions
(Iodine in starch, etc.) this can be catered to older students.
January 24th, 2014
Kellen McDonnell
Page 5
Mystery Mixture
Student Taxonomy Chart
To use: Write down the characteristics of each substance in the table. Afterwards, compare
them to the characteristics of known substances as listed above. If a mystery substance has the
same characteristics as one of the known substances, then you’ve discovered what that
substance is!
LIQUIDS
Float on water or not
Color
Dish Soap
Lamp Oil
Vegetable Oil
HONEY
FLOAT
FLOAT
FLOAT
NOT
GREEN
RED
YELLOW
YELLOW
WATER
NOT
COLORLESS
Substance 1 (water)
NOT
COLORLESS
Substance 2
SOLIDS
Odor or not
Magnetic or Not
Soluble or not
Conductive in water or
not
Salt
Sugar
Sand
Pepper
Steel Wool
Hair
NOT
NOT
NOT
ODOR
NOT
NOT
NOT
NOT
NOT
NOT
MAGNETIC
NOT
SOLUBLE
SOLUBLE
NOT
NOT
NOT
NOT
CONDUCTIVE
NOT
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SUBSTANCE 3
SUBSTANCE 4
SUBSTANCE 5