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19.8 Introduction to the pH Curve for a Weak Acid/Strong Base Titration (Video)

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    Video Topics

    We can say for every one mole of –OH that is added, one mole of weak acid is used and one mole of conjugate base is made. 

    HW + H2O ⇔  H3O+ +  W-

    There are four points on this curve that are especially important

    1) The pH before titration begins:

    0 mol –OH has been added.  The pH is determined by the Ka equilibrium of the weak acid.

    2) The pH at the midpoint of the titration:

    Mol –OH added = ½ mol weak acid initial

    Or mol weak acid = mol conjugate base

    pH = pKa of the weak acid.

    3) The pH at the equivalence point:

    Mol –OH added = mol weak acid initial

    The weak acid has been completely converted to its conjugate base.

    The pH is determined by the Kb reaction of the conjugate base.

    4) Beyond the equivalence point:

    Mol –OH added > mol weak acid initial

    Because the amount of –OH produced by the Kb reaction is small we can say:

    {-OH} = mol of unreacted –OH / Vtotal

    Link to Video

    Introduction to the pH Curve for a Weak Acid/Strong Base Titration: https://youtu.be/Vs5O-HNYo8g

    Attribution

    19.8 Introduction to the pH Curve for a Weak Acid/Strong Base Titration (Video) is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.