Notes:
The final exam will concentrate on material covered since the last exam. It will include basic concepts of geochemical modeling, and will include questions based on your class presentations! A class like this inherently builds on concepts discussed earlier in the semester, so by definition, it is cumulative.

Topics we have discussed since the last exam include
Organic Compounds
Stable Isotopes in Geochemistry
Hydrothermal Alteration of Seafloor
Characterizing Chemistry of Waters, Sampling Methods
Regional Geochemistry - Uranium and Cadmium
Student Presentations, including Geochemical Divides

Example Questions

1. What are delta-D and delta-¹⁸O?
2. Describe and account for the measured delta-D and delta-¹⁸O in meteoric water across North America.
3. Describe a way oxygen isotopes can be used as a paleothermometer.
4. Why do water and steam in geothermal areas usually display a delta-¹⁸O shift, but not a delta-D shift?

2. Weathering of pyrite-bearing shales in North Dakota might lead to the formation of the sulfate mineral
   potassium jarosite, KFe₃(SO₄)₂(OH)₆. Write a balanced equation for the reaction pyrite --> jarosite.
   (Obtain K from the environment).

3. What is pe, and how is it related to Eh? How is it measured?

4. Figure 21.4B in Faure is a mineral stability diagram for aqueous mercury and sulfur species at 25°C and 1 atm pressure. (Show your calculations)
   a. Balance the redox reaction between Hg° and H₂O with HgO.
   b. Using data from Faure Appendix B, derive the equation of the equilibrium line between Hg_(l) and HgO (montroydite).
   c. In which of these two forms is mercury more stable, and how do you know that?

5. In his classic study of the saprolites formed on granitic gneisses in Minnesota, Goldich observed that potassium feldspars weather more slowly than plagioclase feldspars. What could be a reason for such a phenomenon?

Sample exam with key from the University of Washington.