Stability Flashcards
(23 cards)
What is the main focus of the study guide on Stability of Complexes?
Aspects of the stability of complexes
What are stability constants in the context of metal complexes?
Equilibrium constants for the replacement of water molecules with ligands
What is represented by the reaction [M(H2O)n] + L → [M(H2O)n-1L] + H2O?
The stepwise replacement of one water molecule by a ligand (L)
How is the equilibrium constant for the replacement of one water molecule by a ligand (L) defined?
k1 = [ML] / [M][L]
What are the stepwise formation constants also known as?
Stepwise Stability Constants
What trend is observed in the numerical values of stepwise formation constants?
k1 > k2 > k3 > k4 > k5 > k6
What does the overall stability constant (β) represent?
The overall formation constant for the complete replacement of water molecules with ligands
What is the relationship between βn and the stepwise stability constants?
βn = k1 × k2 × k3 × … × kn
Why are log values commonly used for k and β values?
Due to their high values, i.e. 10^30
What is the significance of the Irving-Williams Order in stability constants?
It describes the stability of divalent ions based on ionic potential and size
What is the trend in stability for ions of similar ionic radius with a given ligand?
Stability decreases as the charge decreases
Fill in the blank: The probability of exchanging a water molecule is greater in ______ than in [Ni(H2O)5NH3].
[Ni(H2O)6]2+
True or False: A sudden change in the values of stability constants may occur when L is larger than H2O.
True
What does the symbol for activity (α) represent?
Effective concentration
According to the electrostatic model, what factors are important in the stability of complexes?
Magnitudes of charges and sizes of species
What is the order of stability for the ions: Th4+, Y3+, Ca2+, Na+?
Th4+ > Y3+ > Ca2+ > Na+
What is the expected trend in stability as the ion becomes smaller?
The stability constant gets bigger
What is the example given for a case where stability constants increase?
Ag(H2O)6+ + 2 NH3
What is the statistical explanation for differences in stepwise stability constants?
The probability of exchanging water molecules varies with the number of attachment sites
What is the simplified representation of the reaction when one water molecule is replaced?
M + L → ML
What does β1 equal in terms of k1?
β1 = k1
What happens to the stability of complexes as the ionic potential increases?
Stability increases
