The Case of the Poisonous Gas Introduction Montgomery College Chemistry, Rockville
T. Chen
Gas is all around us and they can often be ignored. But their importance to life cannot be understated
especially in environments when they are lacking, such as deep sea and outer space. In addition to sustaining
life, many gases are also harmful, even deadly, to living things. Chemical warfare had been used to devastating
effects and many dangerous chemicals used in laboratories can also exist in gaseous state under ambient
conditions. Depending on the amount and duration, exposures to poisonous gasses can lead to discomfort such
as shortness of breath, headache, nausea and vomiting. Some poison gas can even be fatal.
Investigation
Gawain has been poisoned! The victim has been suffering from allergic reactions so his nose has been stuffed
up all week while working in lab. Unusual headaches and nauseating feeling have brought him to the doctor
who suspect that Gawain has been a victim of poison. Initial police investigation of the laboratory has obtained
only a trace amount of a gas that appears to be the poison. Due to the limited quantity and instrumental
malfunctions, only very rough analysis were performed on the potential poison. The following are the results
from analysis of the potential poison gas:
The sample has a molecular mass under 100 amu/molecule
The sample appears as a liquid when cooled to -40 oC (using a calcium chlodride hexahydrate ice bath)
The sample is made up of only two different elements.
• • •
Police also recovered 4 suspicious poisonous gas cylinders (found in separately locked cabinets) each belonging
to one of the four other researchers sharing the lab with Gawain. The following are the other researchers who
share the lab with Gawain and the physical properties of the four poisonous gases found in the gas cylinders.
Researcher
Gas name
Density (g/mL)
bp (oC)
Mordred
arsine 1.64 -62.5 -37.6
8.3 0.95 21.1
Morgan
tellurium hexafluoride
0.0106
4.25x10-3
Vivien
phosgene
Vortigern
cyanogen

CHEM131
Montgomery College Chemistry, Rockville
T. Chen
1. Help the police with the investigation! The labels have fallen from the evidences and the four gas cylinders
are now unidentified. The principal criminalist, who is sick at home today, has already examined the four
poisonous gases and has described the procedure and recorded the following data. Help the police to identify the
four cylinders so investigation may continue.
Procedures
Using liquid nitrogen for cooling, all 4 gases were liquefied and 1.00 g of each chemical was introduced to a separate 50.0 mL rigid sealed container, in which the chemicals were allowed to warm up to 25.0 oC. At least 10 minutes waiting time was used to allow all samples to establish thermal equilibrium with the controlled 25.0 oC
environment The pressure measured from the gases in the containers are:
Cylinder ID
P (atm)
A 4.946
B 2.025
C 6.278
D 9.403
*You will need to search for the chemical formulas or molar masses of the suspected gasses to help you match
the labels to the gas cylinders
Cylinder ID
Gas MW (g/mole)
Gas identity
Chemical Formula
A B C D
2. Use the information from the investigations and assuming the poison from which Gawain suffer is one of the
four gases found in the cylinders in the lab, identify the potential poisonous gas. Explain how each clue is used
in arriving at your conclusion.
3. Which researcher would you launch further investigation to better understand the potential motive for