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6: Acid-Base Equilibria in Mixtures

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    • 6.1: Mixtures of Acids
      When solutions contain a mixture of acids or bases, the multiple equilibria may interact. Here we discuss how to predict the pH of solutions that contain multiple acids or bases.
    • 6.2: Polyprotic Acids
      An acid that contains more than one ionizable proton is a polyprotic acid. The protons of these acids ionize in steps. The differences in the acid ionization constants for the successive ionizations of the protons in a polyprotic acid usually vary by roughly five orders of magnitude. As long as the difference between the successive values of Ka of the acid is greater than about a factor of 20, it is appropriate to break down the calculations of the concentrations sequentially.
    • 6.3: Buffers
      A solution containing a mixture of an acid and its conjugate base, or of a base and its conjugate acid, is called a buffer solution. Unlike in the case of an acid, base, or salt solution, the hydronium ion concentration of a buffer solution does not change greatly when a small amount of acid or base is added to the buffer solution. The base (or acid) in the buffer reacts with the added acid (or base).
    • 6.4: Henderson-Hasselbalch Approximation
      The Henderson-Hasselbalch approximation allows us one method to approximate the pH of a buffer solution.
    • 6.5: Acid-Base Titrations
      A titration curve is a graph that relates the change in pH of an acidic or basic solution to the volume of added titrant. The characteristics of the titration curve are dependent on the specific solutions being titrated. The pH of the solution at the equivalence point may be greater than, equal to, or less than 7.00. The choice of an indicator for a given titration depends on the expected pH at the equivalence point of the titration, and the range of the color change of the indicator.
    • 6.6: pH Calculations for Acid–Base Titrations
      In the overview to this chapter we noted that a titration’s end point should coincide with its equivalence point. To understand the relationship between an acid–base titration’s end point and its equivalence point we must know how the titrand’s pH changes during a titration.
    • 6.E: Acid-Base Equilibria (Exercises)
      These are homework exercises to accompany the Textmap created for "Chemistry" by OpenStax.

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