Gen Chem 162 Exam 3 UPDATED ACTUAL QUESTIONS AND
CORRECT Answers
Comparking Ksp of different dissolution stoichiometries You must take into account the different coefficients and use molar solubility
Molar solubility of 2 Ions s= √Ksp
Molar solubility of 3 ions s= ^3√Ksp/4
Molar solubility of 4 ions s= ^4√Ksp/27
, Molar solubility of 5 ions s= ^5√Ksp/108
Common Ion Effect on Solubility Adding a common ion decreases solubility, as the reaction shifts toward the left
to relieve the stress of the excess product. Adding a common ion to a
dissociation reaction causes the equilibrium to shift left, toward the reactants,
causing precipitation (and less ions, therefore decreasing solubility)
The Effect of pH on Solubility The solubility of an ionic compound with a strongly basic or weakly basic anion
increases with increasing acidity (decreasing pH)
Q > Ksp The solution is above saturation, precipitate will form
Q = Ksp the solution is at equilibrium and is saturated
Q < Ksp The solution is unsaturated, no precipitate will form
Selective Precipitation process in which ions are separated using differences in their solubility with a
given precipitating reagent
The ion that precipitates first in selective precipitation The ion with the LOWEST Ksp value --> Since this solid is least soluble, it will
completely precipitate out first before the other solids start to precipitate
When does precipitation begin? When Qsp = Ksp
Lewis Acid electron pair acceptor
Lewis Base electron pair donor
Complex Ion A metal cation bonded to one or more ligands (i.e. lewis bases)
Complex Ion Effect on Solubility Solubility INCREASES when a complex ion forms
Amphoteric Metal Hydroxides metal hydroxides that dissolve in excess base
Amphoteric Metal Hydroxides to memorize Be, Al, Zn, Pb, Sn
Spontaneous Reaction a process that occurs without any ongoing outside intervention
Nonspontaneous Reaction a process that needs ongoing outside intervention to occur
Spontaneity of Reversible Reactions If one process is spontaneous, then the opposite process must be
nonspontaneous (and vise versa)
What does spontaneity depend on? enthalpy and entropy
Entropy (S) a thermodynamic function that is related to the dispersal(or spreading out) of
energy within a system at a given temperature
• the more highly dispersed (or more highly randomized) a given amount of
energy within a system, the more entropy the system has
Microstates and Entropy The more microstates something has, the higher its entropy
CORRECT Answers
Comparking Ksp of different dissolution stoichiometries You must take into account the different coefficients and use molar solubility
Molar solubility of 2 Ions s= √Ksp
Molar solubility of 3 ions s= ^3√Ksp/4
Molar solubility of 4 ions s= ^4√Ksp/27
, Molar solubility of 5 ions s= ^5√Ksp/108
Common Ion Effect on Solubility Adding a common ion decreases solubility, as the reaction shifts toward the left
to relieve the stress of the excess product. Adding a common ion to a
dissociation reaction causes the equilibrium to shift left, toward the reactants,
causing precipitation (and less ions, therefore decreasing solubility)
The Effect of pH on Solubility The solubility of an ionic compound with a strongly basic or weakly basic anion
increases with increasing acidity (decreasing pH)
Q > Ksp The solution is above saturation, precipitate will form
Q = Ksp the solution is at equilibrium and is saturated
Q < Ksp The solution is unsaturated, no precipitate will form
Selective Precipitation process in which ions are separated using differences in their solubility with a
given precipitating reagent
The ion that precipitates first in selective precipitation The ion with the LOWEST Ksp value --> Since this solid is least soluble, it will
completely precipitate out first before the other solids start to precipitate
When does precipitation begin? When Qsp = Ksp
Lewis Acid electron pair acceptor
Lewis Base electron pair donor
Complex Ion A metal cation bonded to one or more ligands (i.e. lewis bases)
Complex Ion Effect on Solubility Solubility INCREASES when a complex ion forms
Amphoteric Metal Hydroxides metal hydroxides that dissolve in excess base
Amphoteric Metal Hydroxides to memorize Be, Al, Zn, Pb, Sn
Spontaneous Reaction a process that occurs without any ongoing outside intervention
Nonspontaneous Reaction a process that needs ongoing outside intervention to occur
Spontaneity of Reversible Reactions If one process is spontaneous, then the opposite process must be
nonspontaneous (and vise versa)
What does spontaneity depend on? enthalpy and entropy
Entropy (S) a thermodynamic function that is related to the dispersal(or spreading out) of
energy within a system at a given temperature
• the more highly dispersed (or more highly randomized) a given amount of
energy within a system, the more entropy the system has
Microstates and Entropy The more microstates something has, the higher its entropy
