Ch6 _ Solubility Flashcards
Def dissolution
Spontaneous reaction of molecules or ions arranged in crystalline structure in contact with solvent
Def precipitation
Solid phase in a liquid solvent, reverse reaction of dissolution
ex of soluble compounds
Compounds with atoms from 1st column
Compounds with ammonium groups (NH4+)
Def solubility
Maximum quantity of a solid able to be dissolved in 1L of solvent (mol/L or g/L)
What is a saturated solution?
Solution containing excess undissolved solid
On what solubility depends?
Salts, pH, temperature & solvent
Solubility product Ksp: def & formula
Equilibrium constant related to the dissolution of a salt in water
Ksp = [Product1]eq^x x [Product2]eq^y
On what solubility product Ksp depends?
Temperature only
What does a smaller K means?
Smaller K means salt less soluble (& pKsp higher)
Relationship between Ksp & pKsp
pKsp = - log(Ksp)
Equilibrium constant for precipitation formula
1/Ksp
Q = [Prod1]^x x [Prod2]^y
What happens when Q
No precipitation formation
Q = [Prod1]^x x [Prod2]^y
What happens when Q>Ks?
Precipitation
Principleoif Le Châtelier
In a saturated solution, adding a quantity of an aqueous reactant will make the reaction consume it, then equilibrium will be in reverse direction. Then solid is formed, so solubility decreases. This is the common ion effect
Decrease of pH lead to…
Decrease of pH leads to decrease of OH leads to increase of solubility
Increase of PH leads to…
Increase of pH leads to increase of [OH-] leads to decrease of solubility
What happens to a basic salt in acidic solution?
Solubility of a basic salts increases in acidic solution
What happens to the solubility of an acidic salt in alkaline solution?
Solubility of an acidic salt increases in alkaline solution
Consequence of precipitation in everyday’s life
Stone kidneys formation
How do we know if precipitation happens? ex of AgCrO4(s)
Q = [Ag+] x [CrO4-]
K = [Ag+]eq x [CrO4-]eq
If Q > K => Precipitation
