STEPHEN LEWIS SECONDARY SCHOOL
SNC 1D SCIENCE
CULMINATING ACTIVITY – CHEMISTRY
IDENTIFY THE MYSTERY SUBSTANCE
PURPOSE
Students will use the terminology and knowledge gained during the Chemistry unit of study to identify
a mystery substance by observing and describing various chemical and physical properties.
SCENERIO
Forensic science is the application of science to criminal investigations (just think C.S.I.). Forensic scientists
collect, analyze and evaluate evidence from a crime scene to be used by law enforcement. Qualitative analysis
(examining physical and chemical properties of a substance) is an integral part of forensic science.
In this activity, you get to play the role of a C.S.I. Your team suspects that a death was caused by the ingestion
of a mysterious white solid. Traces of the solid were found near the victim. The primary suspect in the case
claims that a severe heart attack was the cause of death. It is your responsibility to help your team identify the
mystery solid and decide whether or not it could have been the cause of death.
FORMAT
 The lab portion of the activity will be completed in one period
 You will be given five known white solids and some lab equipment
 Your task is to test these five solids by observing and describing the various physical and chemical
properties
 You will also be provided with the unknown sample found at the crime scene and your job is to determine the
identity of the unknown solid (it’s one of the five you just finished studying)
ANALYSIS
 Record your physical and chemical observations in the table provided and complete the C.S.I. Investigation
Report
 Determine the identity of the mystery solid by comparing the physical and chemical properties of your
unknown substance to the five known substances
 You will answer a set of questions that involve explaining how you arrived at your conclusions. You will also
be asked questions about course content and skills in the context of the lab (just like the Mystery Gases Lab)
CHEMISTRY TOPICS TO REVIEW
 information on a periodic table
 physical properties and chemical properties
 classification of matter
 pure substance vs. mixture
 heterogeneous mixture vs. homogeneous mixture
 element vs. compound
 classify a substance as an element or compound based on its symbol, chemical formula
 classify a substance as a homogeneous or heterogeneous mixture based on its appearance and composition
 identify metals and non-metals by their symbols
 identify the family a metal/non-metal belongs to (alkali, alkaline earth, halogens, noble gases)
 physical change (formation of a mixture, change in state, change in form)
 chemical change and the different types of evidences for chemical change
 count the number of atoms in a chemical formula
 atom vs. molecule
 recognize a molecule by its chemical formula and its picture
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MARKING SCHEME
1. C.S.I. Investigation Report
a) Completion of Table of Observations
b) Correct identity of the mystery solid
c) Rationale for choosing powder
d) Explanation of cause of death
e)
0
0
0
0
1
1
1
1
2
3
2
2
3
4
/10
2. Analysis Questions
3. Safety and Clean-up Protocol
/24
0
1
2
3
4
/4
Total Mark =
/ 38
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INTRODUCTION
In groups of 3-4, you will be investigating the physical and chemical properties of various white solids. You will
record your physical and chemical properties in the tables provided. Make sure each group member records the
observations as you will be using the results to answer analysis questions. Make sure that each group member has a
chance to participate in the testing.
MATERIALS
 Eye protection
 Toothpick or stirring rod
 5 different vials with solids
 Aspirin (C9H8O4)
 Powdered Sugar (C6H12O6)
 Sodium Dihydrogen Phosphate (NaH2PO4)
 Buffered Aspirin (many people have trouble taking aspirin because it upsets their stomach; buffered aspirin
includes an extra ingredient in it known as calcium carbonate (CaCO3) to make it gentler on the stomach)
 Baking Soda (NaHCO3)
 5 bottles that contain each of these solids mixed with water
 Spot plate
 Dilute Hydrochloric Acid, HCl(aq)
 Universal Indicator
 Dilute iron (III) (ferric) nitrate solution, Fe(NO3)3(aq)
 Iodine solution, I2(aq)
PROCEDURE
1. Using a scoopula, add a small amount (tip of your scoopula) of each substance in its solid form to each of the
wells in the SECOND ROW of the spot plate.
2. Using the dropper bottles (shake them well first) fill up the wells half way of the spot plate in the FIRST,
THIRD, AND FOURTH ROW.
3. Use the diagram below to set up.
Substances you will be testing
Sodium
Dihydrogen Buffered Baking Mystery
Aspirin Sugar Phosphate
Aspirin Soda Substance
Universal
Indicator
Testers
sol
sol
sol
HCl
solid
solid
solid
Fe(NO3)3
sol
sol
sol
sol
sol
sol
Iodine
sol
sol
sol
solid
solid
sol
sol
sol
sol
sol
sol
solid
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4. Record the observable physical properties of each solid and record it in Table 1.
5. Examine each of the dropper bottles containing the solids that have been mixed with water. Are these solids
soluble in water? Record your observations in Table 1.
6. Add one drop of universal indicator to each of the five substances in the FIRST ROW of your spot plate.
Mix the contents well using a toothpick/stirring rod. Record your observations in Table 2.
7. Add dilute hydrochloric acid to solid samples of each of the five substances in the SECOND ROW of your
spot plate. Fill up the well in the spot plate to the rim. Record your observations in Table 2.
8. Add 5-6 drops of dilute iron (III) nitrate to each of the five substances in the THIRD ROW. Record your
observations in Table 2.
9.
Add 5-6 drops of iodine to each of the five substances in the FOURTH ROW of your spot plate. Stir. This
reaction may take some time, so be sure to check it before you empty your spot plats. Record your
observations in Table 2.
10. Record the letter of your mystery substance in the space provided on your data sheets.
11. Fill up your spot plate with the mystery substance. Remember to put the solid sample in the SECOND ROW
and the sample mixed with water in the FIRST, THIRD, AND FOURTH row.
12. Record the physical properties of your mystery substance in the table provided.
13. Test and record the chemical changes of your mystery substance in the table provided.
14. Identify your mystery substance as either Aspirin, Powdered Sugar, Sodium Dihydrogen Phosphate, Buffered
Aspirin or Baking Soda.
15. Clean your spot plate well using water and leave everything at your lab bench the same way you found it. Show
your teacher to get your full marks for cleanliness/safety.
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C.S.I. Investigation Report
Investigator________________________
TABLE 1: Physical Properties of the 5 Substances
Substances
Aspirin
(C9H8O4)
State
Physical Properties
Colour
Clarity
Crystal Form
Solubility
Buffered
Aspirin
Baking Soda
Powdered Sugar
(C6H12O6)
Sodium
Dihydrogen
Phosphate
(NaH2PO4)
Buffered Aspirin
(regular aspirin
(C9H8O4) mixed
with some
CaCO3)
Baking Soda
(NaHCO3)
TABLE 2: Chemical Changes of the 5 Substances
Aspirin
Powdered
Sugar
Sodium
Dihydrogen
Phosphate
Universal
Indicator
HCl
Fe(NO3)3
I2
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MYSTERY POWDER LETTER ___________
Now that you’ve carried out these tests, it is your responsibility to identify the mystery powder and determine
whether or not it could have been the cause of death. When you study the physical and chemical properties of the
mystery powder, you observe the following:
Mystery Powder Physical Properties
Mystery Powder Chemical Changes
State
Universal Indicator
Colour
HCl
Clarity
Fe(NO3)3
Crystal Form
I2
Solubility
1. Based upon these results and your original data, the mystery solid at the crime scene was
________________________. (1)
2. Which physical and/or chemical property(s) allowed you to confirm the identity of the mystery powder?
Explain and be very specific by referring to your data. (2)
3. Based on the identity of the mystery powder, I ____________________ (fill in your name), the lead C.S.I. on
this case, __________ (do or do not) believe that the powder was the cause of death in this case. My reasons
are as follows:(3)
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