CSI : What poison was used?
There has been a recent outbreak in poison related deaths in the Phoenix and Scottsdale
area. Victims have been found inside their homes with abnormally high levels of a toxic
substance called Warfarin in their blood. Your job as crime scene investigator is to pin
down the cause of this poisoning outbreak.
After compiling a list of people who have access to warfarin, you ran a background check
to see which have any history of violence, police records, or connections to the victims.
After all that work, you’ve narrowed it down to 4 suspects.
Below is a description of the suspects and what you found when you searched their home
and belongings. Use the chemical clues provided to decide which suspect is the likely
culprit.
Suspect #1
Barry Livingston is the manager of Livingston’s chemical supply. When you search his
house you find a block of a strange substance hidden in a box in the back of his closet.
The block measures exactly 3 cm X 5 cm X 10 cm. Using a balance you measure the
weight of the substance to be 1756.5 g.
1) What substance is this?
Thallium
2) Explain your answer/Show your work:
1756.5/150 = 11.71 g/cm^3 = Thallium
Suspect #2
Sid Shady is an exterminator that works in the Phoenix/Scottdale area. His house has no
traces of toxic chemicals, but when you search his van you find traces of a white
substance in his van. You can’t measure the mass and volume of the powder, so you send
it to the lab for analysis. The lab sends you the following results from a test where they
heated up the substance until it completely evaporated.
Temp. of Unknown Substance vs. Time
Temperture of Substance (Degrees
Celcius)
2000
1800
1600
1400
1200
1000
800
600
400
200
145
136
127
118
109
100
91
82
73
64
55
46
37
28
19
10
1
0
Time (seconds)
3) What substance is this?
Lithium
4) Explain your answer.
First flattening is the mp = 180 C second flattening is the bp = 1340 C = Lithium
Suspect #3
Manny McMilken is a chemist at Arizona State University who studies the effects of
toxic substances on cancer cells. Among the various chemicals in his laboratory you find
one bottle that is not clearly labeled. Manny asks you not to touch it and begins to act
very nervous. He tells you that it is a container cooled by liquid nitrogen and he forgot
what the substance was that was inside. When you open the container you find a solid
metal block. However, as the metal begins to reach room temperature it becomes liquid.
5) What is this substance?
Hg = Mecury
6) Explain how you know.
It is the only metal that is liquid at room temp.
Suspect #4
Loretta Beretta works in the cosmetics industry, and needs access to a lot of different
chemicals and compounds to help make perfumes, oils, and lotions. When you searched
her handbag you found traces of a white substance that you sent to the lab. The lab was
unable to determine a clear melting or boiling point and there was too little of the
substance to determine its density. Instead they tested the solubility of this substance in
water at number of different temperatures. The lab results are below.
Solubility of Unknow n Substance at different tem peratures
substance/ml of H20
mg of unknown
3
2.5
2
1.5
1
0.5
0
1
3.8
6.6
9.4
12.2
15
17.8
20.6
23.4
26.2
tem perature (degrees Celcius)
7) What is this substance?
warfarin
8) Explain your answer
at 20 C you can dissolve 1.7 mg of this substance in 1 ml of water. This is the solubility
of warfarin.
9) From the evidence supplied by your chemical tests, who is the likely murderer?
Explain your answer.
Looks like Loretta Beretta is the culprit since she is the only one with warfarin.
Substance Fact Sheet
Li : Density
0.53 g.cm -3 at 20 °C
Melting point
180.5 °C
Boiling point
1342 °C
Lithium is the first of the alkalis in the periodic table. In nature it’s found like a mixture of the isotopes Li6
and Li7. It’s the lightest solid metal, it’s soft, silvery-white, with a low melting point and reactive. Many of its
physical and chemical properties are more similar to those of the alkaline earth metals than to those of its own
group.
Hg : Density
13.6 g.cm-3 at 20°C
Melting point
- 38.9 °C
Boiling point
356.6 °C
Mercury is the only common metal which is liquid at ordinary temperatures. Mercury is sometimes called
quicksilver. It is a heavy, silvery-white liquid metal. It is a rather poor conductor of heat if compared with
other metals but it is a fair conductor of electricity. It alloys easily with many metals, such as gold, silver, and
tin. These alloys are called amalgams.
As : Density
5.7 g.cm-3 at 14°C
Melting point
814 °C (36 atm)
Boiling point
615 °C (sublimation)
Arsenic appears in three allotropic forms: yellow, black and grey; the stable form is a silver-gray, brittle
crystalline solid. It tarnishes rapidly in air, and at high temperatures burns forming a white cloud of arsenic
trioxide. Arsenic is a member of group Va of the periodic table, which combines readily with many elements.
The metallic form is brittle, tharnishes and when heated it rapidly oxidizes to arsenic trioxide, which has a
garlic odor. The non metallic form is less reactive but will dissolve when heated with strong oxidizing acids
and alkalis.
Tl : Density
11.71 g.cm-3 at 20°C
Melting point
1800 °C
Boiling point
4200 °C
Thallium The element and its compounds are toxic and should be handled carefully. When freshly exposed
to air, thallium exhibits a metallic lustre, but soon develops a blueish-grey tinge, resembling lead in
appearance. A heavy oxide builds up on thallium if left in air, and in the presence of water the hydroxide is
formed. The metal is very soft and malleable. It can be cut with a knife. Thallium is not a rare element; it is
10 times more abundant than silver. Thallium is partially water-soluble and consequentially it can spread
with groundwater when soils contain large amounts of the component. Thallium can also spread by
adsorption on sludge. There are indications that thallium is fairly mobile within soils.
Substance Fact Sheet
1.2 g.cm-3 at 20°C
Warfarin Density:
161-162 degrees C ; 159-165 degrees C
Melting point:
decomposes
Boiling point:
Warfarin was the first anticoagulant rodenticide introduced and was first registered for use in the United
States in 1952 (4, 13). Warfarin is used for controlling rats and house mice in and around homes, animal and
agricultural premises, and commercial and industrial sites. It is odorless and tasteless and effective in very
low dosages. Action is not rapid; usually about a week is required before a marked reduction in the rodent
population is noticeable. Warfarin is practically insoluble in water (1.7 mg/100 ml at 20 degrees C)
Cd : Density
8.7 g.cm-3 at 20°C
Melting point
321 °C
Boiling point
767 °C
Cadmium is a lustrous, silver-white, ductile, very malleable metal. Its surface has a bluish tinge and the
metal is soft enough to be cut with a knife, but it tarnishes in air. It is soluble in acids but not in alkalis. It is
similar in many respects to zinc but it forms more complex compounds. About three-fourths of cadmium is
used in Ni-Cd batteries.uman uptake of cadmium takes place mainly through food. Foodstuffs that are rich in
cadmium can greatly increase the cadmium concentration in human bodies. Examples are liver, mushrooms,
shellfish, mussels, cocoa powder and dried seaweed.An exposure to significantly higher cadmium levels
occurs when people smoke. Tobacco smoke transports cadmium into the lungs. Blood will transport it
through the rest of the body where it can increase effects by potentiating cadmium that is already present
from cadmium-rich food.
V : Density
6.1 g.cm-3 at 20°C
Melting point
1910 °C
Boiling point
3407 °C
Vanadium is a rare, soft, ductile gray-white element found combined in certain minerals and used
mainly to produce certain alloys. Vanadium resists corrosion due to a protective film of oxide on the
surface. Common oxidation states of vanadium include +2, +3, +4 and +5.