CHEM 1001 Chapter Notes - Chapter 18 : Supersaturation, Ionic Compound
29 Jun 2018
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CHAPTER 18: Solubility and Complex-Ion Equilibria
18.1 Solubility Product Constant, Ksp: for eqbm established between solid
solute & its ions in a saturated solution; varies with temperature. Reaction is solid
dissociated ions
18.2 Relationship Between Solubility and Ksp
Solubility can be converted to mol/L and becomes concentration of each ion
with coefficient 1. Basically, molar solubility = x, or can represent it as “s”,
so can also solve for “s” through Ksp value and remember to account for
coefficients.
18.3 Common-Ion Effect in Solubility
Solubility of ionic compound is lowered if common-ion present from before,
especially if solid isn’t that soluble.
18.4 Limitations of the Ksp Concept
Salt effect: diverse ion effect that increases [ions] b/c diff. ions are there.
[ions] calculated isn’t accurate due to ion-pairs, which increase the higher the
electrostatic attraction between ion (like higher charges). Solute doesn’t completely
dissociate.
18.5 Criteria for Precipitation and its Completeness
Qsp (ion product): If Q > Ksp, supersaturated and precipitation occurs. If Q
< Ksp, unsaturated and no precipitate. If Q = Ksp, saturated. This criteria
only applies after dilution has occurred (like if 3 drops of something are
added, conc. changes)
Precipitation is considered complete if %ion remaining is less than 0.1%.
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Document Summary
18. 1 solubility product constant, ksp: for eqbm established between solid solute & its ions in a saturated solution; varies with temperature. Solubility can be converted to mol/l and becomes concentration of each ion with coefficient 1. Basically, molar solubility = x, or can represent it as s , so can also solve for s through ksp value and remember to account for coefficients. Solubility of ionic compound is lowered if common-ion present from before, especially if solid isn"t that soluble. Salt effect: diverse ion effect that increases [ions] b/c diff. ions are there. [ions] calculated isn"t accurate due to ion-pairs, which increase the higher the electrostatic attraction between ion (like higher charges). Qsp (ion product): if q > ksp, supersaturated and precipitation occurs. This criteria only applies after dilution has occurred (like if 3 drops of something are added, conc. changes)
