1. (10 points) Give a specific example for each of the following terms:
a) an element
b) a compound
c) a diatomic molecule
d) a CFC
e) a greenhouse gas
2. (10 points) Write a balanced reaction for the combustion of methane, CH4. Assume plenty of oxygen is available.
3. (10 points) When the DEQ examines your automobile, it is tested for hydrocarbons and CO in the exhaust, among other things. Explain why these might be found in the exhaust and why they indicate an engine that is not working completely efficiently.
4. (10 points) Calculate about how many molecules of water are in a 12 oz. glass of water. Assume 12 oz of water weighs 355 grams.
5. (15 points) Natural bromine consists of about equal amounts of Br-79 and Br-81.
These are called different ________________________ of bromine.
For each form of bromine, indicate the composition of one atom in terms of protons, neutrons and electrons.
Br-79:
Br-81:
Explain why the Periodic Table shows the atomic mass of bromine as 79.9.
6. (10 points) Describe the evidence that stratospheric ozone is being destroed, including the evidence that CFCs contribute to this effect (Nobel Prize work).
7. (15 points) Explain why carbon typically has a valence of four.
Write a good Lewis electron dot structure for a carbon compound that has four single bonds.
Write a good Lewis electron dot structure for a carbon compound that has two double bonds.
Write a good Lewis electron dot structure for a carbon compound that has one single bond and one triple bond.
Write a good Lewis electron dot structure for a carbon compound that has one double bond and two single bonds.
Can you think of any other combinations of bonds that carbon could do?
8. (10 points) Write a rough graph that corresponds to the following situation.
In order to determine the temperature of hot water, you allow it to cool until the temperature reaches 40°, which takes 10 minutes. Then you allow it to cool further until the temperature reaches 30°, which takes another 5 minutes.
Explain how you might use your graph to determine the original temperature.
Also explain the limitations of this technique and how confident you could be that you obtain the correct original temperature. What experiments might you do to determine whether this technique is accurate?
9. (10 points) Write a good exam question that you wish I had asked (and answer it).
(Graded based on relevance, imagination, difficulty, and correctness of your answer)