Fractional Precipitation Pogil Answer Key [patched] (2025)

If you have a solution containing equal concentrations of two anions, such as Chloride ( Cl−Cl raised to the negative power ) and Chromate ( CrO42−CrO sub 4 raised to the 2 minus power ), and you slowly add Silver ions ( Ag+Ag raised to the positive power ), two competing equilibria exist:

Therefore, AgI(s) will begin to precipitate when [Ag⁺] ≈ 8.5 × 10⁻¹⁶ M.

Fractional precipitation is the sequential removal of ions from a solution by adding a specific precipitating agent.

Many "Level 3" POGIL questions ask how much of the first ion remains in solution when the second ion begins to precipitate. To solve this, take the fractional precipitation pogil answer key

A standard POGIL problem involves a solution containing two anions, such as Cl−cap C l raised to the negative power Br−cap B r raised to the negative power , to which a cation like Ag+cap A g raised to the positive power

[Ag+]=8.5×10-170.10 M=8.5×10-16 Mopen bracket Ag raised to the positive power close bracket equals the fraction with numerator 8.5 cross 10 to the negative 17 power and denominator 0.10 M end-fraction equals 8.5 cross 10 to the negative 16 power M

A typical POGIL problem will provide a solution containing two ions—for example, . You are asked what happens when silver nitrate ( AgNO3AgNO sub 3 ) is slowly added. If you have a solution containing equal concentrations

Ksp=[Ag+][Cl−]cap K sub s p end-sub equals open bracket cap A g raised to the positive power close bracket open bracket cap C l raised to the negative power close bracket

1.8×10-10=[Ag+](0.10)1.8 cross 10 to the negative 10 power equals open bracket cap A g raised to the positive power close bracket open paren 0.10 close paren

This guide is intended for students to check their work and deepen understanding, not to bypass the learning process. Use this as a study aid after attempting the POGIL activity on your own. To solve this, take the A standard POGIL

The final questions in a POGIL activity usually ask you to determine how much of the first ion remains in solution right before the second ion starts to precipitate. We know starts precipitating when The Calculation: Plug this specific value back into the Kspcap K sub s p end-sub expression to find the remaining

This part explores how the common ion effect can be used to manipulate solubility and improve the efficiency of separations.

A typical POGIL exercise guides you through a scenario where a solution contains two different anions (e.g., Cl−Cl raised to the negative power CrO42−CrO sub 4 raised to the 2 minus power ) and a cation (e.g., Ag+Ag raised to the positive power

Solve for the concentration of the added ion (the "titrant") required to start precipitation for each species.

[Ag⁺] = Kₛₚ(AgCl) / [Cl⁻] = (1.8 × 10⁻¹⁰) / (0.10) = 1.8 × 10⁻⁹ M