PLS 671: Environmental Soil Chemistry

Instructional Objectives for Final Exam
  • Be able to predict the thermodynamic favorability of a chemical reaction.
  • Distinguish between: (a) elementary and overall reactions; (b) homogeneous and heterogeneous reactions.
  • Use Pauling’s Rules to predict ion coordination.
  • Be able to calculate various parameters related to phyllosilicate clay minerals (net negative charge, CEC, molecular weight, and clay activity) and predict the mineralogy in the sample.
  • Understand the relationship of clay mineralogy to potassium (K+) fixation and water sorption.
  • Know different surface area methods and relate to clay mineral structure.
  • Differentiate between soil organic matter (SOM) fractions and be aware of diagnostic humification indicators.
  • Discuss major functional groups on SOM that contribute to the observed CEC as a function of pH.
  • Calculate ionic strength (I) for both symmetrical and nonsymmetrical electrolytes. 
  •  Be able to perform pH calculations for weak acids/bases and strong acids/bases (of the monoprotic type).

  • Understand the relationship between ion activities and concentrations.

  •  Given equilibrium expressions for common metal oxides and clay minerals in soils, derive equations necessary to plot   solubility diagrams and be prepared to make interpretations.
  •  Given equilibrium expressions for complexation and hydrolysis of metals and nonmetals, be able to perform calculations of free and complexed species.
  • Know the purpose for each reagent used in the soil fractionation procedure and diagnostic features for identification of soil minerals.

  •  Know the definitions of Lewis acids and bases and how these terms are applied to soil components.

  •  Understand the procedures and calculations involved to calculate CEC of your soil in the lab.

  • Be prepared for basic analytical calculations employed in the lab.

  • Distinguish between different adsorption isotherm and ion exchange equations.  Be able to calculate thermodynamic parameters related to sorption.

  • Know definitions of PZNC, PZNPC, PZC, PZSE and methods of determination.

  • What are the effects of I on the thickness of the double layer (1/k)?  Know those parameters which influence 1/k.

  • Understand the chemistry of soil components such as reactive sites, surface charge components of solid particle surfaces, and solution chemistry of inorganic solutes to predict reactivity.

  • Be able to explain the ion preference patterns for group I alkali metals.

  • Predict sorption mechanisms for cations and anions on soil mineral surfaces.

  • Distinguish between heterovalent and homovalent ion exchange.

  • Be prepared to derive and calculate half-lives (t1/2) for first and second order reactions and rate constants.  Also, write expressions for the overall rate given a reaction.  Be familiar with the equation used to express the temperature dependence of rates.

  • Given reduction half-reactions, be able to construct and sketch Eh/pe versus pH diagrams, and predict the direction of the reaction.

  • Understand the general controls on the redox state of natural waters.

  • Be acquainted with the soil N, Mn, Fe, and C cycles and how they can impact contaminant fate.