Chapter 17 Acid-Base Titrations

Strong Acid- Strong Base H+ + OH-  H2O K = 1/Kw = 1 x 1014 Note: pH = 7 at equivalence point pH changes rapidly near equivalence point

Adding acid to base:

Weak Acid-Strong Base HA + OH- → A- + H2O K = 1/Kb Running alkali into the acid Note: pH > 7 at equivalence point pH changes more slowly near the eq. pt. flat buffer region leading up to eq. pt.

Strong Acid- Weak Base H+ + A-  HA K = 1/Ka Running acid into the alkali Note: pH < 7 at eq. pt. pH changes slowly near eq. pt. buffer region leading up to eq. pt

Go to this link and scroll down to “explore these ideas below” Go to this link and scroll down to “explore these ideas below”. Look at the differences between the different titration curves by turning them on and off. http://www.avogadro.co.uk/chemeqm/acidbase/titration/phcurves.htm

Choice of Indicator HIn ↔ H+ + In- HIn and In- have different colors, the color of solution depends upon the ratio of concentrations Ka = = end point occurs when [H+] = Ka or when pH = pKa (of the indicator!)

Choose your indicator to have a pKa near the pH of the equivalence point of your acid-base reaction.

Take the notes quiz here. https://docs.google.com/spreadsheet/embeddedform?formkey=dC1RcUF0dXREVGxPaTVlWmhUb3RqNkE6MQ