Screencast 7.1
www.youtube.com/watch?v=pkqDTi2K-5g
This screencast walks you through how to calculate the equilibrium constant for an acid-base reaction.

Screencast 7.2
www.youtube.com/watch?v=V8oR7FpKptc
This screencast walks you through the derivation of the Henderson-Hasselbalch equation.

Screencast 7.3
www.youtube.com/watch?v=KeIyTqEHMEY
This screencast walks you through the way pH changes in a titration.