19.8 Introduction to the pH Curve for a Weak Acid/Strong Base Titration (Video)
- Page ID
- 342603
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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
-
Prof. Steven Farmer (Sonoma State University)