- Aligned with Big Idea 1 and Learning Objective 1.20
- Emphasizes Science Practices 2, 3, 4, 5, 6, and 7
Determine the concentration of calcium in milk by complexometric titration. Teach this laboratory experience using either the guided activity or inquiry activity. In the guided activity, students prepare and standardize a solution of EDTA and use it to determine the concentration of calcium in milk. Both the standardization and sample titrations are done 3 times and the average of the values used in the calculations.
The inquiry activity allows students to design a procedure to determine the concentration of calcium in milk and requires them to account for interfering substances such as magnesium and other transition metals. The inquiry activity provides an opportunity for students to present their experiment design and results, reinforcing the practice of communicating findings. Detailed preparation and procedure notes guide you through leading a successful inquiry exercise, including a suggested rubric for assessing student performance.
Both activities include Big Idea assessment questions that follow the format of the AP® Chemistry Exam free-response questions. In the Big Idea assessment, students consider another complexometric titration, the titration of zinc in zinc lozenges with EDTA, and calculate the concentration of zinc in the lozenge based on data provided. They also are required to consider what to do if they forget to standardize their titrant before they titrate the zinc.
This kit provides the following AP® Chemistry experiences: design a procedure to collect data, analyze data, perform error analysis, write and balance chemical equations, use volumetric glassware, standardize a titrant, and perform multiple trials. Analyzing calcium in milk engages students and makes the concepts covered more interesting. Materials are sufficient for 30 students working in teams of 3. Digital teacher’s manual, included FREE with kit purchase or sold separately, is a 12-month eBook license to the Complexometric Titration of Calcium in Milk 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.