Aquation

Question 1

Aquation in Octahedral Complexes

Main reaction

Answer 1

[CoCl(NH3)5]2+ + H2O —> [Co(NH3)5(OH2)]3+ + Cl-

Question 2

Aquation in Octahedral Complexes

Rate equation

Answer 2

Rate = Ka[CoCl(NH3)5]2+ + Kb[CoCl(NH3)5]2+ * [OH-]

Question 3

Aquation in Octahedral Complexes

Reactions for Ka

Answer 3

1) Identify that term is relating Dd mechanism!
2) This means that for complex [CoCl(NH3)5]2+, it goes

MLnX -> MLn + X (RDS)

MLn + Y -> MLnY

Question 4

Aquation in Octahedral Complexes
(Kb and its relevant reactions)

4 reactions, 1 of them being an equib.

Answer 4

Equilibrium: [CoCl(NH3)5]2+ + OH- equibarrow [CoCl(NH3)4(NH2)]+ + H2O

RDS(Dd): [CoCl(NH3)4(NH2)]+ -> [Co(NH3)4(NH2)]2+ + Cl-

R1: [Co(NH3)4(NH2)]2+ + H2O -> [Co(NH3)4(NH2)(OH2)]2+

R2: [Co(NH3)4(NH2)(OH2)]2+ + H+ —> [Co(NH3)5(OH2)]3+

Question 5

Aquation of Octahedral Complexes

Why is Kb bigger than Ka?

Answer 5

In Kb, the Cl- ligand leaves from a + charge compared to Ka where the Cl- ligand leaves from a 2+ charge meaning the rate will be higher for Kb as it is easier to remove as there is less attraction to the Cl- ligand in Kb