| 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.
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.
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
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0.53 g.cm -3 at 20 °C
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Melting point
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180.5 °C
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Boiling point
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1342 °C
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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.
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Hg : Density
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13.6 g.cm-3 at 20°C
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Melting point
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- 38.9 °C
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Boiling point
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356.6 °C
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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.
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As : Density
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5.7 g.cm-3 at 14°C
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Melting point
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814 °C (36 atm)
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Boiling point
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615 °C (sublimation)
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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.
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Tl : Density
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11.71 g.cm-3 at 20°C
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Melting point
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1800 °C
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Boiling point
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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
Warfarin Density:
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1.2 g.cm-3 at 20°C
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Melting point:
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161-162 degrees C ; 159-165 degrees C
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Boiling point:
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decomposes
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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)
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Cd : Density
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8.7 g.cm-3 at 20°C
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Melting point
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321 °C
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Boiling point
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767 °C
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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.
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V : Density
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6.1 g.cm-3 at 20°C
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Melting point
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1910 °C
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Boiling point
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3407 °C
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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.
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