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End of Year report prep and review

Lassen Astrobiology Student Intern Program. End of Year report prep and review. A Year in Review: Water Chemistry From Field to Lab. Photo Credit: National Park Service. Talk Outline. Review Water Chemistry Activities to Date. Warner Valley Trip. Online Assignments.

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End of Year report prep and review

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  1. Lassen Astrobiology Student Intern Program End of Year report prep and review A Year in Review: Water Chemistry From Field to Lab

  2. Photo Credit: National Park Service Talk Outline • Review Water Chemistry Activities to Date • Warner Valley Trip • Online Assignments • Andesite Dissolution Experiment • Review Core Concepts • pH and Conductivity • Chemical Reactions & Equilibrium • Solubility Rules and Other Factors That Affect Solubility • Putting it All Together • Connecting the Conceptual Dots • Discuss Experimental Results: Do They Validate Field Observations? • Parallels Between Field, Lab & Mars

  3. Photo Credit: National Park Service Water Chemistry Timeline • Warner Valley Trip • pH and Conductivity Lab Competition • Field Sampling of Warner Valley Sites (Acid, Alkaline & Neutral) • Temp, pH and Conductivity • Anion and Cation Samples • Online Assignments • Assignment 1: Water • Bent Structure Makes Water Polar • Assignment 1.5: Aqueous Solubility • Periodic Trends of Solubility • Rocks & Minerals • Chemical and Physical Properties of Solution Affect Solubility • Andesite Dissolution Experiment • Andesite Subjected to field-like conditions • Analyze Rock Powder Before and After Experiment • Measure pH, Conductivity Throughout Experiment • Cation and Anion Samples Before and After Experiment

  4. Photo Credit: National Park Service Review Core Concepts • pH • Measure of hydrogen ions in solution • Defined as -log [H+] • Log is base 10 • pH <7 is acidic, pH >7 is basic • Conductivity • Measure of total ions in solution • More ions, more conductivity • Some ions conduct better than others

  5. Review Core Concepts • Spontaneous Reactions • Reactants and Products CH4 (g) + 2 O2 (g) CO2 (g) + 2 H20 (g) • Equilibrium Reactions • Forwards and backwards reactions NaCl(s) [Na+](aq) + [Cl-](aq) • Increasing a common ion can push reaction in reverse

  6. Review Core Concepts • Solubility rules 1: If a compound contains a Group 1A or Group VIIA element (except F), then it is soluble. 2: If the compound contains sulfate (SO42-), it is usually soluble. 3: Nitrates (NO3-) and ammonium salts (NH4+) are soluble. 6: Unless paired with a soluble cation from rules 1 & 3, all hydroxides (OH-), carbonates (CO32-), oxides (O2-) , phosphates (PO43-) and silicates (SiO44-) are insoluble. 4: If the compound contains a group IIA element, then it is usually soluble. 5: Unless paired with a soluble anion from rules 1-3, if the compound contains a transition metal, or especially a IIIA or IVA metal, then it is insoluble.

  7. Review Core Concepts • Other Solubility Factors • Temperature • pH

  8. Photo Credit: National Park Service Putting it All Together • Connecting Conceptual Dots • Conductivity Reflects Number of Ions in Solution • Dissolution is an Equilibrium Reaction • Silica is More Soluble in Base • Transition Metal Minerals are More Soluble in Acid FeOH(s) [Fe+3](aq) + 3[OH-](aq)

  9. Photo Credit: National Park Service Putting it All Together • pH and Conductivity Results for Acid Group

  10. Photo Credit: National Park Service Putting it All Together • XRD Results for All Groups • Unaltered Andesite • Neutral 60C Rock Powder • Acid 60C Rock Powder • Alkaline 60C Rock Powder • Rise in Clay Peak at 19

  11. Photo Credit: National Park Service Putting it All Together • Cation Results

  12. Photo Credit: National Park Service Putting it All Together • pH and Conductivity Results Indicate Andesite Dissolution but Potential Precipitation of Different Minerals • XRD Patterns Indicate Formation of Clay Minerals • Relative Experimental Cation/TDS Results Correspond to Relative Field Values • Clays Observed at Devil’s Kitchen • Clays Observed at Mars’ Gale Crater by Curiosity Rover

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