HCl and NaOH, a strong acid - strong base titration? Citric acid and NaOH, a weak, triprotic acid - strong base titration? Do your students standardize the NaOH solution as a first step?
As a second year AP teacher, I am full of questions about acid-base chemistry pedagogy. College Board's AP Insight program lays out guided inquiry activities to address this core "challenge area." The activities build students' conceptual understandings of the following topics:
- Strong acids
- Bronsted-Lowry theory
- Weak acid and weak base net ionic equations
- Significance of strong conjugate acids and strong conjugate bases producing additional H+ and OH-
- pH and pOH calculations
- Dissociation equations and ICE charts for weak acids and bases
- Neutralization equations and ICL charts for strong acids and bases
- Titrations curves (equivalence points, half-equivalence points, buffering regions)
- Bond strengths and understanding acid-base strength
- How buffers work
- Setting up a buffer
These performance tasks have helped me tremendously this year, and I am feeling more confident about my students' conceptual knowledge.
However, the AP exam seems to regularly ask a free response question about titration. Like everyone else, we are pushed for time. Some veteran AP teachers suggest using a virtual lab, some suggest doing a demonstration, others suggest a full standardization of NaOH with a strong acid titration, and still others have encouraged a weak acid titration as they believe buffer systems are only understood when experienced. Can my students be successful if we don't titrate a weak acid? Can my students adequately answer the free response question if I wait to titrate in lab until after the exam? What is your opinion? I can't be the only new AP teacher wondering, right?