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Precipitation Analysis. Considering the formation of solid from solution. Q vs. Ksp Ion Analysis. How to predict whether a precipitate will form when two solutions are mixed?. Investigate Qsp vs. Ksp at initial concentrations Q = Ksp “Saturated” solution occurs. No changes.
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Precipitation Analysis Considering the formation of solid from solution. Q vs. Ksp Ion Analysis
How to predict whether a precipitate will form when two solutions are mixed? • Investigate Qsp vs. Ksp at initial concentrations Q = Ksp “Saturated” solution occurs. No changes. Q > Ksp Precipitates will form until saturated. Equilibrium shifts left. Q < Ksp NO precipitate forms. Solid dissolves. Equilibrium shifts right.
Sample Exercise p. 734 • Predict whether precipitate will form? Q > Ksp PPT will form!
Selective Precipitation • Mixtures of metals in solutions are separated using a technique called selective precipitation. • Using a reagent whose anion forms a precipitate with only one or a few of the metals in the mixture. • Sulfide salts (sulfide ion) is often used!
Qualitative Analysis of Cations • Separating mixtures into five major categories based on solubility. #1. Insoluble Chlorides #2. Insoluble sulfides in Acids. #3. Insoluble sulfides in Bases. #4. Insoluble carbonates. #5. Alkali metals and ammonium ions.