- Aligned with Big Idea 1 and Learning Objective 1.19
- Emphasizes Science Practices 2, 3, 4, 5, 6, and 7
Students determine the identity of 2 unknown Group I metal carbonates using gravimetric analysis. This rigorous laboratory exercise can be taught using either a guided or an inquiry activity. In the guided activity, the first step is to precipitate the carbonates with excess calcium ions. After drying, the mass and moles of the resulting calcium carbonate are determined. From that data, students calculate the formula mass of the unknown Group I metal carbonate and identify the Group I metal.
The inquiry activity allows students to design a procedure for precipitating aqueous carbonate ions from 2 unknown Group I metal carbonates and analyzing the data to identify the unknown metal. It also 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 write and balance the chemical equation for the calcium chloride and sodium carbonate reaction, determine whether there are sufficient calcium ions to precipitate all the carbonate ions, and calculate the mass of calcium carbonate produced. Students also apply their gravimetric analysis skills to determine mass of silver in silver ore.
This kit provides the following AP® Chemistry experiences: design a procedure to collect data, analyze data, perform error analysis, calculate percent error, write and balance chemical equations, perform stoichiometric calculations, and identify limiting reagents in reactions. The use of sodium carbonate and potassium carbonate as the unknowns makes this procedure safer than traditional procedures that use heavy-metal carbonates. Materials are sufficient for 30 students working in pairs. Digital teacher’s manual, included FREE with kit purchase or sold separately, is a 12-month eBook license to the Gravimetric Analysis of a Carbonate teacher’s manual. You can also access the digital student guide for this kit for free at
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