Answer Key Best — Fractional Precipitation Pogil

The fraction of Cl⁻ remaining is (1.3 × 10⁻⁵ M) / (0.0010 M) = 0.013, or about 1.3% .

| Step | Action | Calculation | | :--- | :--- | :--- | | | Calculate [Ag⁺] needed to precipitate AgI. | [Ag⁺] = Ksp(AgI) / [I⁻] = (8.5 × 10⁻¹⁷) / (0.010) = 8.5 × 10⁻¹⁵ M | | 2 | Calculate [Ag⁺] needed to precipitate AgCl. | [Ag⁺] = Ksp(AgCl) / [Cl⁻] = (1.8 × 10⁻¹⁰) / (0.010) = 1.8 × 10⁻⁸ M | | Conclusion | Identify the first precipitate. | Since it takes far less Ag⁺ (8.5 × 10⁻¹⁵ M) to start precipitating AgI, AgI will precipitate first . | | 3 | Calculate remaining [I⁻] when AgCl starts. | When AgCl just starts, [Ag⁺] = 1.8 × 10⁻⁸ M . Use the Ksp of AgI: [I⁻] = Ksp(AgI) / [Ag⁺] = (8.5 × 10⁻¹⁷) / (1.8 × 10⁻⁸) = 4.7 × 10⁻⁹ M . |

A common "critical thinking" question in POGILs asks how much of the first ion remains in the solution when the second ion just begins to precipitate. To find this, take the required for the second ion ( from the example above) and plug it back into the Kspcap K sub s p end-sub expression for the first ion: fractional precipitation pogil answer key best

modeled after the POGIL structure?

Fractional precipitation is a powerful analytical chemistry technique used to separate ions from a solution based on their differing solubilities. In many advanced chemistry courses, Process Oriented Guided Inquiry Learning (POGIL) activities are used to help students derive these complex chemical principles independently. The fraction of Cl⁻ remaining is (1

To determine if this is an effective quantitative separation, calculate the percentage of iodide remaining in solution:

To help you check your calculations on a specific problem, let me know: | [Ag⁺] = Ksp(AgCl) / [Cl⁻] = (1

Compare the two calculated concentrations of the adding agent ( precipitates at precipitates at is smaller than , .

First, identify the two potential precipitates and write out their equilibrium equations.

): This equilibrium constant calculates the maximum amount of solid that can dissolve in an aqueous solution. A smaller Kspcap K sub s p end-sub