Chemistry Module Quiz Key
1. Write definitions for the following terms. (3 points each)
a. Isotopes Atoms that have the same number of protons but different numbers of neutrons.
They have the same atomic number but different mass numbers.
b. Precursor (according to the CWC) According to the CWC, any chemical reactant that takes
part at any stage in the production by whatever method of a toxic chemical.
c. Neurotransmitters Chemicals that transmit signals from nerve cells (neurons) to a target cell
across a synapse.
d. Potential energy
position or state.
A retrievable, stored form of energy an object possesses by virtue of its
e. Exothermic change Change that leads to heat energy being released from the system to the
surroundings.
f.
Burning or deflagration
Relatively slow oxidation (propagation less than the velocity of
sound).
g. Detonation Very fast oxidation (propagation greater than speed of sound).
h. Secondary high explosive A high explosive that is more stable than primary high explosives
but can be detonated by a devise such as a blasting cap (e.g. TNT and RDX)
2. As you know, nerve gases are phosphorus-containing organic compounds that disrupt the process
by which nerves transfer messages to organs. The disruption is caused by deactivating the enzyme
acetylcholinesterase, leading to a buildup of the neurotransmitter acetylcholine. Draw a Lewis
structure that corresponds to the line drawing below of acetylcholine. Note that the nitrogen does
not have its most common bonding pattern. It has four bonds and no lone pairs. (4 points)
3. The sulfur mustard that we talked about in class is just one of several compounds with similar
structures and properties.
a. Phosphorus trichloride, PCl3, is one of the substances that can be used to make sulfur mustards.
Draw its Lewis structure and sketch its molecular geometry, including bond angles. (8 points)
b. PCl3 is a schedule 3, part B substance according to the Chemical Weapons Convention.
Explain what that means. (4 points)
Schedule 1, Part B substances are chemicals that are used in the manufacture of chemical
weapons but that also have legitimate large-scale industrial uses.
c. The sulfur mustard with the Lewis structure below is called O-mustard or T. Sketch its line
drawing. (4 points)
d. In general terms, describe the effect that sulfur mustards have on the body. (4 points)
Sulfur mustard forms a sulfonium ion, which attaches to the guanine nucleotide of DNA,
disrupting cell division and function. This can lead to cellular death or cancer.
Although people exposed to mustard gas may not exhibit immediate symptoms, within 24 hours
of exposure to mustard agent, victims experience intense itching and skin irritation, which
gradually turns into large water blisters. If there is exposure to the eyes, the eyelids swell,
causing temporary blindness. If inhaled, mustard sulfur mustards cause bleeding and blistering
within the respiratory system. Severe mustard gas burns are often fatal.
4. Consider the following structures. (20 points)
A.
B.
C.
D.
a. Which of the structures would you expect to be a chemical weapon? Explain your choice.
Structure C represents an organophosphate, and therefore would be expected to represent a
nerve gas. It represents Soman.
b. Which of the structures would you expect to be a chemical explosive? With reference to the
three criteria for a substance to be a chemical explosive, explain your choice. (Hint: There’s an
important and subtle component of your answer that relates to the comparison of the predicted
bond angles around a carbon atom bonded to four different atoms and the actual bond angles
between carbon atoms in the structure.)
Structure D would represent an explosive. When it decomposes, it would form a lot of gas. The
carbon would form carbon dioxide gas, CO2(g), and the nitrogen would form nitrogen gas,
N2(g). With the nitro groups attached to the carbons, the reaction would take place quickly.
Each carbon is attached to four different atoms, so we would expect the bond angles to be about
109.5, but the angles in a cube are 90. This would make the structure relatively unstable and
therefore have high potential energy. Because the products would be much more stable, we would
expect a lot of energy to be released.
c. Which of the structures would you expect to be a Schedule 1, Part A substances for the CWC?
Why?
Substance C, which is Soman, has no use other than as a chemical weapon, so it is a Schedule 1,
Part A classification.
d. Which of the structures would you expect to be a Schedule 1, Part B substance for the CWC?
Why?
Schedule 1, Part B substances are used in the manufacture of chemical weapons and have no, or
very limited, uses outside of chemical warfare. Substance B is a precursor to substance C.
5. I got the impression that the class thought it would be useful to try to think like a terrorist in order
to help develop policies relating to combatting terrorism. Let’s assume that you are a terrorist trying
to decide between using phosgene and Sarin for a chemical attack. What are the pros and cons of
the use of each for your purposes? What information would you search for to help make the
decision as to which chemical to use? (12 points)
There are many different answers to this. My first thought was that because phosgene is less
dangerous, it would be safer to make and easier to transport. Also, because it used extensively in the
chemical industry, it might be more easily obtained. If the goal is maximum casualties, Sarin is a
better choice, but if the goal is just to cause some casualties and psychological distress, phosgene might
be the better choice.
6. In general terms, explain why some chemical reactions, such as those associated with chemical
explosives, release energy. (10 points)
7.
7. The following is from the Organisation for the Prohibition of Chemical Weapons (OPCW) website.
Article IX is a key provision of the Chemical Weapons Convention. It grants each Member State the
right to request an on-site challenge inspection of any facility or location of another Member State in
order to resolve questions concerning possible non-compliance with the Convention. Such inspections
might be conducted anywhere and without delay by an inspection team designated by the OPCW
Director-General in accordance with the Convention’s Verification Annex. No OPCW Member
State has requested a Challenge Inspection since the Organisation was established in 1997. But the
Conference of the States Parties has at various stages requested that the Technical Secretariat
maintain a high standard of readiness to conduct such inspections and to report any problems that
may arise therein. Accordingly, the Technical Secretariat regularly holds exercises at headquarters
level and in the field, as well as table top exercises, and regularly reports on its readiness to the
Executive Council. From 31 October to 4 November 2011, the Kingdom of Thailand and OPCW
will co-organise the 6th challenge inspection field exercise, with the Technical Secretariat’s
participation funded by contributions from the European Union. This will be the first challenge
inspection field exercise held in an Asian country.
Describe the purpose of the OPCW and use your description to explain why they would help
organize this exercise. (6 points)
The OPCW is the “implementing body of the [CWC]…given the mandate to achieve the object
and purpose of the Convention, to ensure the implementation of its provisions, including those
for international verification of compliance with it, and to provide a forum for consultation and
cooperation among States Parties.”
The exercise described above is important for achieving the objectives of the CWC, including
verification, and co-organizing the operation with the Kingdom of Thailand encourages
cooperation among countries.