Suppose a solution contains 0.1 M AgNO3, 0.1 M NaCl, and 0.1 M NaNO3. If HCl is added to the solution, what will happen?
threshold was crossed. Only then did the second precipitate begin to form. At this point, the beaker held two distinct layers of solids, and the separation was complete. ✅ The "Answer Key" Summary
is a method used to separate a specific ion from a mixture by adding a reagent that forms a precipitate with only one of the ions at a time. It is a selective precipitation technique based on the idea that the less soluble compound (lower Kspcap K sub s p end-sub ) will precipitate before the more soluble compound (higher Kspcap K sub s p end-sub ) as the concentration of the precipitating ion increases. Core Concepts in the POGIL Activity Solubility Product Constant ( Kspcap K sub s p end-sub ): Indicates the solubility of a compound in solution. Reaction Quotient ( Qspcap Q sub s p end-sub fractional precipitation pogil answer key best
[Cl−]=1.8×10-103.46×10-6=5.2×10-5 Mopen bracket Cl raised to the negative power close bracket equals the fraction with numerator 1.8 cross 10 to the negative 10 power and denominator 3.46 cross 10 to the negative 6 power end-fraction equals 5.2 cross 10 to the negative 5 power M Step 4: Evaluate Separation Efficiency
generally dictates a less soluble salt, meaning it requires far fewer ions to initiate solid formation. : If , the solution is unsaturated. No precipitate forms. If Suppose a solution contains 0
[Ag+]=Ksp(Ag2CrO4)[CrO42−]open bracket Ag raised to the positive power close bracket equals the square root of the fraction with numerator cap K sub s p end-sub open paren Ag sub 2 CrO sub 4 close paren and denominator open bracket CrO sub 4 raised to the 2 minus power close bracket end-fraction end-root
The key should explain why you choose one ion over another using Ksp expressions. For example: “To precipitate AgI first, we calculate [Ag⁺] needed = Ksp(AgI)/[I⁻]. Compare to [Ag⁺] needed for AgCl. The lower [Ag⁺] wins.” Only then did the second precipitate begin to form
Let’s work through a typical problem. This mirrors what you’d find in a high-quality compilation.
Ksp = [A⁺][B⁻]
To determine if the separation was successful, calculate the percentage of the first ion remaining in solution: