Fractional Precipitation Pogil Answer Key Best -

Question:
A solution contains 0.010 M Cl⁻ and 0.010 M I⁻. Solid AgNO₃ is added dropwise. Using the (K_sp) values below, calculate the [Ag⁺] required to begin precipitation of each salt. Which precipitates first?

| Salt | (K_sp) | |------|------------| | AgCl | (1.8 \times 10^-10) | | AgI | (8.5 \times 10^-17) |

Model Answer:

For AgI:
(K_sp = [Ag^+][I^-] \Rightarrow [Ag^+] = \fracK_sp[I^-] = \frac8.5 \times 10^-170.010 = 8.5 \times 10^-15 , M) fractional precipitation pogil answer key best

For AgCl:
([Ag^+] = \frac1.8 \times 10^-100.010 = 1.8 \times 10^-8 , M)

Conclusion: AgI requires a much lower [Ag⁺] ((8.5 \times 10^-15 M)) to precipitate than AgCl ((1.8 \times 10^-8 M)). Therefore, AgI precipitates first.

Why this answer is correct:
The salt with the smaller (K_sp) requires a lower concentration of the common ion to reach saturation. This is the cardinal rule of fractional precipitation. Question: A solution contains 0

Before diving into answer keys, let's recap the science. Fractional precipitation is a technique used to separate two or more ions (e.g., Cl⁻, I⁻, or Ba²⁺, Ca²⁺) from an aqueous solution. It relies on adding a precipitating reagent (like AgNO₃ or Na₂SO₄) drop by drop. The ion that forms the least soluble compound (lowest Ksp) will precipitate first.

Key Concept: The ion with the smallest Ksp value requires the lowest concentration of the precipitating agent to begin forming a solid.

Drug synthesis often yields mixtures of halide salts (Cl⁻, Br⁻). Fractional precipitation with silver nitrate can isolate the desired compound. Which precipitates first

Before we dissect the POGIL answer key, let’s establish the science. Precipitation occurs when two ions combine to form an insoluble solid. However, when a solution contains two different cations (e.g., Ag⁺ and Pb²⁺) or two different anions (e.g., Cl⁻ and I⁻), adding a single precipitating agent can cause one solid to form before the other.

Fractional precipitation is the process of separating ions by exploiting differences in their solubility product constants ((K_sp)). The less soluble compound (smaller (K_sp)) precipitates first as you slowly add a reagent.