EARTH 421: GEOCHEMISTRY 2

Transcription

1 EARTH 421: GEOCHEMISTRY 2 Course Syllabus 2012 Instructor: Carol Ptacek EIT 5001 tel.: ext ptacek@uwaterloo.ca Teaching assistants: Krista Paulson EIT 1012 tel.: ext kmapauls@uwaterloo.ca Ou Alana Wang EIT 1012 tel: ext o3wang@uwaterloo.ca Schedule Lectures: Tuesday, Thursday: 9:30-10:20 am - Room: RCH 306 Labs: Thursday: 10:30-11:50 am; Friday: 12:30-1:50 pm Room: EIT 1009 CALENDAR DESCRIPTION OF EARTH 421 The application of chemical thermodynamics to geochemical problems. Development of the three Laws of Thermodynamics; Gibbs free energy and equilibrium constants. Introduction to various topics in aqueous geochemistry, such as mineral equilibrium, ion exchange and redox equilibrium. Laboratory sessions will involve various experiments related to mineral solubility, chemical kinetics, acid-base equilibrium and chemical modeling. WHAT IS THE PRINCIPAL OBJECTIVE OF THIS COURSE? To provide an understanding of the basic principles of thermodynamics as they relate to problem solving in various applications of geochemistry. WHY THERMODYNAMICS? Thermodynamics offers Earth Scientists a powerful additional tool to aid in their interpretation of Earth processes. It can be used to delineate the physicochemical conditions that led to a particular mineral assemblage; to discern whether a mineral assemblage could have resulted from equilibrium or disequilibrium (kinetic-controlled) conditions; to aid in decision-making in 1

2 exploration geochemistry or to design engineered geochemical barriers and containment systems in Environmental Hydrogeology. In this course, we develop only the most relevant areas of thermodynamics to enable its practical application to problem solving in various areas of Earth Sciences; from high temperature/pressure applications in the solid earth to understanding processes in surface and near-surface hydrogeochemical systems. APPROACH OF STUDY IN THIS COURSE Begin with an examination of the behaviour of gases Develop thermodynamic principles most relevant to geochemical systems Understand the concepts of chemical equilibrium and metastability Develop conceptual and empirical models to describe geochemical systems Apply thermodynamic principles to solve geochemical problems. Provide a basic understanding of chemical processes in aqueous systems LEARNING RESOURCES A set of overhead images and some supplementary material have been prepared for this course and are available on the course website. These will serve as a useful base for adding your own notes and ideas generated during class. Course concepts are more fully developed in the course textbook: Geochemical Thermodynamics, 1994, by D.K. Nordstrom and J. L. Munoz, Blackwell Scientific Publ. Co., 492 pp. (QE515.5T46N67) Other references that you may find helpful are: Aqueous Environmental Geochemistry, 1997, by Donald Langmuir, Prentice Hall, New Jersey, 600 pp. (GB855.L36) Geochemistry, Groundwater and Pollution (2 nd Ed.), 2005, by Appello and Postma, Balkema Publ., Netherlands, 536 pp. (QE516.4A77) 2

3 LECTURE TOPICS The following topics will be examined during lectures, approximately in the order presented LECTURE TOPIC Thermodynamics of Gases Ideal and real gases, compressibility factors, critical T and P, corresponding states, the Van der Waal and Redlich-Kwong equations. Calculating compressibilities, the Newton-Raphson method, steam separation in geothermal systems. Systems, State Functions and the 1st Law Closed, open, isothermal and adiabatic systems. The first law of thermodynamics. Enthalpy (H) and its variation with temperature (heat capacity - Cp), additivity rules for State Functions, conventions for standard state. The 2nd law Reversible reactions and maximum work. Entropy (S) and its variation with temperature. The physical meaning of entropy. Free Energy (G) and Fugacity (f) P-T relationships of thermodynamic properties, the Clapeyron Equation and its application to geologic systems, determining mineral phase transitions points. G and the partial pressures of gases, calculating fugacities. Thermodynamics of Solid and Solution Mixtures Activities, chemical potentials and other partial molal quantities. The Gibbs-Duhem equation and application to geothermometry. The derivation of the equilibrium constant (K) from the first and second laws. Geochemical Applications Equilibrium constants and the Van t Hoff Equation. Geochemical applications of chemical equilibria. A comprehensive look at gypsum/anhydrite equilibria. The 3rd Law The need for the third law and the evidence; where thermodynamic data originates and its limitations. Dissolved substances and activity coefficients Standard states for aqueous species, ion activity coefficients, the Debye-Huckel and Davies equation. The Paint Pot Problem A comprehensive example of applying thermodynamics to geochemical exploration. APPROXIMATE TIME SPENT ON TOPIC 0.5 weeks 3

4 EARTH 421 Geochemistry 2 Course Syllabus Physiochemical Properties of Aqueous Solutions Hydration, hydrolysis, acid-base equilibrium, speciation nomenclature, the carbonate system, ph distribution diagrams. Mineral and Gas Solubility Solubility products and saturation indices; the influence of ion hydrolysis on mineral and gas solubilities. The Carbonate System A comprehensive examination of carbonate gas-watersolid equilibrium and the factors that influence it. A look at analogous geochemical systems. Additional Topics in Aqueous Geochemistry Time permitting 0.5 week? ASSIGNMENTS There will be five course assignments. Each assignment must be answered clearly with neatly prepared diagrams. Some of the assignments involve the use of chemical modeling programs freely available on the internet: SUPCRT, STEAMTAB and PHREEQCI. Students can use Google to locate and download these programs at any time on their own but they are also available in the Programs folder on the course web site. Supporting information from computer program output must be clearly annotated. Any late assignment, undocumented work or work that does not show a suitable level of professional pride is not acceptable. Two assignments involve writing your own small computer program. The use of spreadsheets is allowed but not recommended if you have already taken a programming course. Free FORTRAN compilers are available at this link: and UW s IST site lists a number of programming options and services at: LABORATORIES AND MATERIALS REQUIRED The labs in EARTH 421 are designed to illustrate various concepts in thermodynamics or aqueous equilibria that are developed in the lecture material or acquaint you with analytical or computational skills. Other important information pertaining to the labs includes the following: 1. There will be 5 or 6 labs of 2 hours each scheduled approximately every two weeks throughout the term. 2. Materials required for labs are simply pencils, a straight edge, calculator, and a notebook. All other material will be provided in the labs. 3. Some written material may be required to hand in at the end of the lab period. Other material may be required to hand in at the beginning of the next lab session in two weeks time. No material will be accepted after this two week deadline. 4. Each individual must turn in a completed exercise to receive credit unless otherwise 4

5 indicated. Submitted labs or assignments that are the result of group efforts (when permitted) should bear the names of all the contributors. 5. There will be short quizzes given before the labs, but not a separate lab exam. The conceptual material from the labs will be integrated into the midterm and final exams. EVALUATION GUIDELINES The marking breakdown for the course (±5% on each component) is as follows: 20% Laboratories including pre-laboratory quizzes 20% Assignments and in-class quizzes 20% Midterm (To be held Tuesday, October 30, during class time) 40% Final exam (2.5 hours, date and location TBA) Please note that accommodation for missed labs, midterm or final exam may be considered only if you show the instructor the original of a Verification of Illness Form (VIF). Holiday travel plans are not acceptable grounds for granting any accommodation. Ample time will be given for completing laboratory reports or course assignments, so submissions past the deadline date will not be accepted. If you miss the midterm due to a verified illness, the final exam will count for 60% of your final grade. There will be no make-up mid-term. ACADEMIC INTEGRITY Studying and working in groups to learn material is a very valuable practice and is encouraged (and even required for the laboratories). If you do work together on an assignment, the names of all the team members must appear on the covering page. This is also true when it comes to submitting computer programs or spreadsheets. We have had instances in the past where students have made cosmetic changes to the variable names in a program that was written by someone else and then submitted it as their own. This is plagiarism. All students registered in the courses of the Faculty of Science are expected to know what constitutes academic integrity, to avoid committing academic offences, and to take responsibility for their actions. When the commission of an offence is established, disciplinary penalties will be imposed in accord with Policy #71 (Student Academic Discipline). For information on categories of offences and types of penalties, students are directed to consult Policy #71 ( If you need help in learning what constitutes an academic offence; how to avoid offences such as plagiarism, cheating, and double submission; how to follow appropriate rules with respect to 5

6 group work and collaboration; or if you need clarification of aspects of the discipline policy, ask your TA and/or your course instructor for guidance. Other resources regarding the discipline policy are your academic advisor and the Undergraduate Associate Dean. All perceived academic offences will be reported to the Office of the Dean of Science for further investigation. An informative web site on plagiarism and related academic offences can be found at: Students who believe that they have been wrongfully or unjustly penalized have the right to grieve; refer to Policy #70 (Student Grievance) at: FOR STUDENTS WITH DISABILITIES The Office for Persons with Disabilities (OPD), located in Needles Hall, Room 1132, collaborates with all academic departments to arrange appropriate accommodations for students with disabilities without compromising the academic integrity of the curriculum. If you require academic accommodations to lessen the impact of your disability, please register with the OPD at the beginning of each academic term. 6