Chemistry Detectives
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Copyright 2009 General Electric Company
What is Chemistry Detectives?
This experiment teaches a little analytical chemistry by letting kids sort out the mystery chemicals from a list of
unknowns. They can do all five unknowns or only one, depending on the attention span of the kids and how
busy we are. You can also adjust the complexity of the unknown based on the age of the kids—flour is pretty
simple to figure out while salt vs. sugar is a little trickier to distinguish.
Why is Chemistry Detectives important?
Teaches problem solving and introduces some physical property understanding
Goal of experiment
Use chemistry for problem solving.
Items needed for the experiment
• Clear glass cups/ pitcher/ measuring cups
• One or more of the following
Cabbage Juice: Buy one red cabbage and boil it in water for a bout 2 hours, smell up
kitchen! Pour juice into a container. This is your indicator solution.
• Cream of tartar (the potassium salt of tartaric acid, KHC4H4O6, a weak acid)
• Baking soda (mainly sodium bicarbonate, NaHCO3, a weak base)
• Table salt
• Sugar
• Flour
Instructions for the demonstration
With spatula, place solid in vial, enough to cover bottom of vial. Label vial or make
sure you know which number solid went into each vial.
Add about 1/3 to ½ way full of water. Swirl and determine if solid dissolves.
Record your observation. If solid even partly dissolves we say it is soluble.
Add a few drops of indicator solution (smelly red cabbage juice). Note the color
change if any.
Add a few drops of vinegar. Note a “reaction” if any. A reaction will be bubble
formation. This part of the experiment is the “volcano” experiment where vinegar
(acetic acid) reacts with sodium bicarbonate to make carbon dioxide (gas).
Conclusions
Notes/Results of experiment.
Applications
Forensics: Is unknown solid good or bad?
Know about common solids around the house: are they acid, base or neutral? Do
they dissolve in water? Do they react with vinegar?
* If multiple experiments, please repeat Goals of Experiment to Conclusions.
Worksheet
5 Unknown Solids
Chemist___________________________________________
Data
Sample #
Soluble?
Indicator Color
React with vinegar?
No
Solid Dissolves
Floats
Flour
Yes
Add Indicator
Turns Pink
No Change
(purple)
Cream of Tartar
Sugar
Turns Green
or Blue
Yes
Tide
Neutral
Basic
Reacts with
Vinegar
No
ACID
Baking Soda
This is an excellent first time activity to introduce chemistry for later elementary. Students
love this real “scientist work”, it is fairly easy and safe, and lends itself to why questions to
investigate further.
NYS Standard 4: The Physical Setting
Key Idea 3: Matter is made up of particles whose properties determine the observable
characteristics of matter and its reactivity.
P.I. - 3.1 Observe and describe properties of materials, using appropriate tools.
3.1a
3.1b
3.1c
3.1e
3.1f
3.1g
P.I. – 3.2 Describe chemical and physical changes, including changes in states of
matter.
3.2a
3.2b
3.2c
NYS Standard 6: Interconnectedness: Common Themes
Key Idea 5: Identifying patterns of change is necessary for making predictions about future
behavior and conditions.