Fractional Precipitation Pogil Answer Key ★ [Confirmed]

value always precipitates first. POGIL models will quickly show you that this is only true if the compounds have the same ion-to-cation ratio (e.g., both are 1:1 electrolytes like AgClcap A g cap C l AgBrcap A g cap B r

expression if the chemical formula has coefficients greater than one (e.g., the concentration of silver is squared in the expression).

An insoluble solid that forms when two clear solutions are mixed. Kspcap K sub s p end-sub

Example B — Carbonate precipitation of Zn2+ and Cu2+ (common POGIL) fractional precipitation pogil answer key

If you are working through a POGIL and find yourself stuck, keep these tips in mind: Always write out the balanced dissolution equation first.

[Ag+]=1.8×10-100.10 M=1.8×10-9 Mopen bracket cap A g raised to the positive power close bracket equals the fraction with numerator 1.8 cross 10 to the negative 10 power and denominator 0.10 M end-fraction equals 1.8 cross 10 to the negative 9 power M Step 2: Calculate required to precipitate Ag2CrO4cap A g sub 2 cap C r cap O sub 4

begins to form, this is considered a highly effective analytical separation. 4. Tips for Navigating Your POGIL Answer Key value always precipitates first

substance to solve for the remaining concentration of the first cation. Answer Summary

This requires careful application of equilibrium principles. Since AgI has already been precipitating, the solution remains saturated with respect to AgI at this point. Using the Kₛₚ expression:

Ksp=[Ag+]2[CrO42−]cap K sub s p end-sub equals open bracket Ag raised to the positive power close bracket squared open bracket CrO sub 4 raised to the 2 minus power close bracket Kspcap K sub s p end-sub Example B

values to determine the precipitation order. You must explicitly calculate the concentration of the added ion for both equations.

Step 3 — Order of precipitation:

Fractional precipitation occurs when a reagent is added slowly to a solution containing multiple ions. As the concentration of the precipitating reagent increases, the compound with the lower solubility product constant ( Kspcap K sub s p end-sub