Chem1 Acids and Bases

If you teach General Chemistry at any level, you teach some aspects of acid-base chemistry-- but how much of this are your students able to LEARN in the limited time that is usually available? All too often we consider ourselves successful if we can get a majority of the class to recognize some of the major groups of acids and bases, to identify conjugate species, and convert between hydronium ion concentration and pH. Even in more advanced courses where equilibrium calculations are done, it is as much as we can do to get most students beyond the simplest weak-acid pH and buffer solution problems.

Which is too bad, considering the many applications of the subject to other chemical topics, and to later courses in analytical chemistry, biochemistry, and environmental chemistry.

The Chem1 Acid-Base lessons are intended to help build a thorough conceptual understanding of all aspects of acids and bases in aqueous solutions. In order to provide maximum flexibility, we have divided the lessons into two sets of nine lessons each. Many of these are divided into sublessons, individually selectable through a simple menu system. Over 50 discrete, selectable lesson segments are available.

Part 1: Fundamental Concepts

Part 1 is devoted mainly to the qualitative aspects of acid-base chemistry. Although it covers pH, it does not deal with equilibrium calculations, and it may therefore be all you need for an introductory course that does not include these topics. One theme of modern acid-base chemistry that runs through these lessons (and which is continued in Part 2) is the idea of relative proton [free] energy; in the form of the "proton ladder" introduced in Lesson 3 , this concept will be found to materially aid students in understanding the leveling effect and in predicting the direction and extent of proton transfer reactions.

Summary of Contents

Please see the Instructor's Guide for a detailed description of these lessons.

  1. Introduction: the hydrated proton
  2. Proton ping-pong: conjugate species
  3. The fall of the proton: acid-base reactions
  4. Recognizing common acids and bases
  5. Reactions of acids and bases; salts
  6. The pH scale
  7. Acid-base titrations
  8. Acid names drill
  9. Drill: is it acidic, basic, or neutral?


 

Part 2: Equilibria and Calculations

Part 2 deals with acid-base equilibria and calculations. Because most such calculations involve approximations of various kinds, some effort is devoted to helping students understand the rationale behind these approximations and the limits of their applicability.

Considerable emphasis is placed on the way that the pH influences the distribution of conjugate species in acid-base systems; use of the modern proton-energy source/sink concept of acids and bases and log-concentration vs. pH plots help students visualize what is going on in such solutions. More importantly, the plots serve as a means of predicting the pH of a solution of an acid, ampholyte, or conjugate base without carrying out numerical calculations. This enables students to understand and deal with polyprotic systems such as carbonate and phosphate, and with zwitterions.

Summary of Contents

As can be seen from the following list, some topics in this lesson extend beyond the material that is conventionally included in a first-year General Chemistry course. Many of these will be ideal in more advanced courses in analytical, environmental, clinical, and technical chemistry, in which the earlier units can serve as review.

Please see the Instructor's Guide for a detailed description of these lessons.

  1. Acid-base equilibria in aqueous solutions
  2. How the pH controls the composition
  3. Solutions of strong acids
  4. Monoprotic weak acid calculations
  5. Buffer solutions
  6. Bases, salts, and hydrolysis
  7. Graphical estimation of pH
  8. Polyprotic systems
  9. Carbonates and natural waters

 

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