CSI Training: Chemical Properties OL
In order to prepare yourselves for the upcoming trial in which you must be an expert witness, you will need to
participate in a chemical properties training session.
You will be presented with 4 known substances that have very similar physical properties. You will test these substances
to determine their chemical properties.
Then, you will be presented with a mystery substance that has similar physical properties to the known substances you
have just tested. You must test the unknown substance and compare your results to the known substances in order to
identify the mystery substance.
You will follow up with a report of your findings.
Procedure:
1. Read and note (in writing) the important information from your background information guide. (On the back of
these instructions.)
2. Answer these RESEARCH questions: What are chemical properties? How do you determine the chemical
properties of a substance?
3. Place small amounts of the known substances in the labeled circles on your lab sheet.
4. Test each substance with a few drops of vinegar, water and iodine.
5. In an organized and careful manner, record your observations.
6. Ask the lead CSI agent for the mystery powder found at the crime scene and gathered for evidence.
7. Record your observations of the physical properties of the mystery substance.
8. Test the mystery powder with a few drops of vinegar, water and iodine.
9. Use your notes from the background information guide, your notes on the physical properties and your findings
from the tests of the known substances to determine the identity of the mystery substance.
You will submit a report of your findings to the lead CSI (that would be your teacher) for evaluation, using the following
format. You will use your findings to help you determine the identity of the evidence you will be presenting to the jury.

1.
2.
3.
4.
5.
6.
Heading
o Title
o Date
o Name
Notes from background information guide
Answer the RESEARCH questions above
Organized record of your observations
Determination of the identity of your mystery substance
Explanation of the specific evidence that lead you to your conclusion
Respond to analysis questions below (in complete sentences)
ANALYSIS QUESTIONS
1.
2.
3.
4.
What were the physical properties that were similar amongst all of the substances?
Which substances had the same chemical properties?
What was/were the chemical property(s) they shared?
How did discovering the chemical properties of the substances help you to identify the unknown substance?
CSI TRAINING BACKGROUND INFORMATION GUIDE FOR TESTING FOR THE CHEMICAL PROPERTIES OF SPECIFIC
SUBSTANCES.
Baking soda (NaHCO3) : Sodium Bicarbonate: This substance has multiple uses including causing baked goods to rise,
used as a mild abrasive in toothpaste, used as an antacid, and used as a mild abrasive in cleaning products. It is also
known as a base. CAUTION: DO NOT GET IN YOUR EYES.
Corn Starch: This is a fine powdery starch (a carbohydrate consisting of a large number of glucose molecules) from the
corn kernel. It is widely used as a thickener in cooking. This is a neutral substance.
Baby Powder: This is made from talc which is a mineral that is composed mainly of magnesium, silicon and oxygen. It is
used to prevent chafing or rashes on baby’s diaper area. This is a neutral substance.
Baking Powder: This is made up of sodium bicarbonate (NaHCO3) and tartrate salt (KHC4H4O6). It is used as a leavening
agent in baked goods (it makes things rise). It is a combination of an acid and a base. CAUTION: DO NOT GET
IN YOUR EYES.
Water (H2O): The most common liquid on Earth. It is a neutral substance.
Vinegar: This is a liquid solution of acetic acid (CH3COOH) and water (H2O). It is an acid used in cooking and cleaning
products. This will react with a base.
Tincture of Iodine: This is a dark brown or yellowish liquid made up of iodine and alcohol. It is used as a disinfectant.
Iodine turns black when it comes in contact with a starch. CAUTION: DO NOT GET IN YOUR EYES.
IODINE WILL STAIN SKIN AND CLOTHING.
Additional information:
Temperature changes, bubbling or fizzing, explosions, color changes, formation of precipitate and light production all
indicate that a chemical change has occurred. A hydrophobic substance is one that repels water. Acids and
bases always react with one another.