- Aligned with Big Idea 6 and Learning Objective 6.13
- Emphasizes Science Practices 1, 2, 3, 4, 5, 6, and 7
This laboratory exercise combines the traditional skills of titration to determine acid concentration with insightful use of the Henderson-Hasselbalch equation to determine pKa. It can be taught using either a guided or an inquiry activity. In the guided activity, students titrate the acetic acid in vinegar and use their titration data to determine the acid’s concentration and pKa.
In the inquiry activity, students develop their own procedure to determine an acid’s concentration in a solution and pKa. The inquiry activity provides an opportunity for students to present their experimental design and results, reinforcing the practice of communicating findings. Detailed preparation and procedure notes guide you through leading a successful inquiry activity and include a suggested rubric for assessing student performance.
Both activities include Big Idea assessment questions that follow the AP® Chemistry Exam free-response question format. In the Big Idea assessment, students compare and contrast the titration of a weak acid by a strong base with the titration of a strong acid by a strong base. Students draw titration curves and explain the curves’ shapes based on what happens at the molecular level.
This kit provides the following AP® Chemistry experiences: design a procedure to collect data; analyze data; prepare and standardize a solution; determine the concentration of an analyte; and use volumetric glassware, such as a buret and volumetric pipet. Lab preparation time is minimal because students prepare and standardize their own sodium hydroxide solution using potassium hydrogen phthalate (KHP). Materials are sufficient for 30 students working in groups of 3. Digital teacher’s manual, included FREE with kit purchase or sold separately, is a 12-month eBook license to the Concentration of Acetic Acid in Household Vinegar teacher’s manual. You can also access the digital student guide for this kit for free at
AP® is a trademark registered and/or owned by the College Board®, which was not involved in the production of, and does not endorse, these products.