Section 2A: Solubility, Ksp, and Complex Ions......................Jenni Morris and Aaron Elinoff
•Solubility is the quantity of a particular substance that can dissolve in a particular solvent
(yielding a saturated solution)
Henry's Law:
Sg = kHPg
•Sg = gas solubility (M)
•kH = Henry’s law constant (M/mmHg)
•Pg = partial pressure of the gaseous solute (mmHg)
Le Chatelier's Principle:
Gas + liquid solvent <----> saturated solution + heat energy
•A change in any of the factors determining equilibrium causes the system to shift.... In this
case, the reaction shifts left
•For the Reaction:
AaBb(s) <----> aAb+(aq) + bBa+(aq)
–The solubility expression is:
Ksp = [Ab+]a[Ba-]b
and
Q = [Ab+]a[Ba-]b
•What’s the difference between Q and Ksp?
–Q is used for a chemical reaction that is not necessarily at eq.
–Q = Ksp, the system is at equilibrium and is saturated
–Q < Ksp, the system is not at eq. and is not saturated
–Q > Ksp, the system is not at eq. and is supersaturated
The Common Ion effect
•Using:
Ksp = [Ag+][Cl-] = 1.6x10-10
•We know:
(x)(x) = 1.6x10-10
•And:
x = [Ag+] = [Cl-] = 1.3 x 10 -5
•So what if we added 0.10 mol of NaCl to 1 liter of AgCl solution?
•[Ag+][Cl-] = 1.6x10-10
[Ag+](0.10M) = 1.6x10-10
[Ag+] = 1.6x10-9
Complex Ions
•A complex ion is formed by combination of simpler ions or molecules
–Example: Co2+ combines with 6 H2O to form the complex ion
Co(H2O)62+