[AdiDex]

We've done preparation of Tetraamminecopper(II) sulphate [Cu(NH3)₄(H2O)_n]SO4 using copper sulphate and 50% ammonia solution. Initially, a pale blue colour of Cu(OH)₂ appeared with turbidity then after a dark blue colour solution is obtained. It is a substitution reaction.

Initially, why formation of Cu(OH)₂ is taking place ??

Is NH₃  acting as base and ripping off the proton from the complex [Cu(H2O)₆]²⁺ ? Then on the further increment of the concentration of NH₃, it starts to act as Nucleophile?? My high school teacher taught me that acid-base reactions are always fast, so in this example is everything is about kinetics? What is the role of the thermodynamics? From where can I get a quantitative explanation with proper data?

[Borek]

Google for copper hydroxide solubility product and amine copper complexes stability constants.

It is all about thermodynamics, no kinetics required to explain these observations.