Chem. 31 – 5/13 Lecture

Announcements I Lab Stuff –Remaining of Lab Reports (including resubmissions) due Thursday (no late lab reports accepted afterwards) Final Exam: –Monday 5/18 (10:15 to 12:15) –~60% new material; ~40% review material –150 points; so about 50% longer than other exams –Allowed one sheet (8.5” x 11”) of notes

Announcements II Today’s Lecture –Chapter 10: Questions –Review of Material –Teaching Evaluations

Chapter 10 – Acid Base Titrations Example Questions 1.A chemist does a test titration for a weak acid present at 0.10 M with a strong base and notices only moderate sharpness. a)Will titrations at M be improved or worse? b)Will the same indicator be ideal at lower concentrations? 2.Looking at the titration curve below, what type of titration was performed? a)strong base by strong acid b)diprotic base by strong acid c)base mixture by strong acid d)diprotic acid by strong base pH V(acid)

Topics Since Exam 2 Chapter 22 –How to determine relative retention (  ) from chromatogram and what it is a measure of* –How relative retention can be changed –How to determine N and H for a column from chromatogram* –How to determine resolution from chromatogram* –What factors can be adjusted to improve resolution

Topics Since Exam 2 Chapter 8 –Solution of weak acid problem (using ICE method)* –Solution of weak base problem (using ICE method)* –Determination of fraction of association/dissociation* –Knowledge of when ICE method fails –Solution of buffer problems (both weak acid/conjugate base and weak acid/strong base or weak base/strong acid types)*

Topics to Know Since Exam 2 Chapter 9 –Identification of type (e.g. H 2 A vs. H 2 L + vs. H 2 L 2+ ) and form (acid, intermediate, or base) of polyprotic acids (including charge on groups) –Determination of species concentration when any form (H 2 A, HA -, or A 2- ) is dissolved in water* –Buffer problems involving polyprotic acids* –Determination of fractions of acid present in each form (monoprotic to diprotic acids) or concentration of each form when pH is known*

Topics to Know Since Exam 2 Chapter 10 –Determination of pH as a function of volume of added acid or base for strong acid/strong base titrations* –What factors affect precision and accuracy of a titration using indicators –Determination of pH as a function of volume of added acid or base for weak acid/strong base titrations* –How pK a and concentrations affect titration curve –Determination of pH as a function of volume of added acid or base for weak base/strong acid titrations* –The shape of acid-base titration curves for mixtures and diprotic acids