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Solubility of Salts & Complex Ions. Solubility of Salts. Precipitation reactions occur when one of the products in a double replacement is a water-_________ compound. Predicting Solubility. The good guys are ALWAYS soluble. #1 NO CHO CLO N. ClO 3 - ClO 4 -. Alkali metals. NO 3 -.
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Solubility of Salts • Precipitation reactions occur when one of the products in a double replacement is a water-_________ compound
Predicting Solubility • The good guys are ALWAYS soluble #1 NOCHOCLON ClO3- ClO4- Alkali metals NO3- C2H3O2- NH4+
Other Ions • Halogens are mostly ______; except with Ag, Pb • OH- are mostly ______; except with CaBaSr • CO32-, PO42-, S2-, and SO32- are mostly ________.
Solubility of Insoluble Salts • “Insoluble” means that less than 0.01 mole dissolves per liter • SOME still dissolves according to an equilbrium expression.
Solubility Product ConstantKsp • The equilibrium constant that reflects the solubility of a compound • “sp”: solubility product • AgBr(s) <---> Ksp = 5.4 x10-13 • Appendix J lists Ksp values
Practice Problems • Write the equililibrium expressions for the solid in water. 1) BaF2 (s) 2) Ag2CO3 (s)
Calculating Ksp from Solubility • In a saturated solution of BaF2, 0.063 grams of the compound is dissolved in 100 mL. Use this information calculate the Ksp for BaF2. BaF2 (s) <--> Ba2+(aq) + 2F-(aq)
Estimating the Salt Solubility from Ksp • The Ksp of Ag2CO3 is 8.5 x 10-12. What is the concentration of Ag2CO3, Ag+, and CO32- dissolved? Convert Ag2CO3 concentration to g/L.
What volume of water is required to dissolve 1 gram of Ag2CO3?
Solubility & the Common Ion Effect • The solubility of a salt is lowered by the presence of a common ion in the solution. (LeChatlier's) • Write the reaction and expression for the solubility of Zn(OH)2.
Practice Problem • Calculate the solubility in mol/L of Zn(OH)2 in the presence of 0.010M Zn(NO3)2, • Ksp of Zinc Hydroxide = 3.0 E-17
Ksp and Q (reaction quotient) • Q reflects concentration of ions ___________________ . • K reflects the concentration of ions __________________ . Q = Ksp: __________________ Q < Ksp: __________________ Q > Ksp: __________________
Precipitation Reaction • If the concentration of Mg2+ is 1.5x10-6 M and the concentration of OH- is 1.0x10-4 M, will precipitation of Mg(OH)2 occur? Ksp = 5.6x10-12.
Precipitation Reactioncont • If the concentration of magnesium remains 1.5x10-6 M, what concentration of the hydroxide ion is needed to precipitate magnesium hydroxide?
Precipitation Reactions • The value for the Ksp of of AgBr is 5.0E-13. Write the Ksp expression. • A student mixes 10 mL of 1.5 x 10-4 M AgNO3 with 2.0 mL of 5.0x10-4 M NaBr and stirs. What will the student observe? Justify with a calculation.