[WahooMan]

I'm pretty lost with this, so please bare with me. Any help is very very much appreciated.

In testing the relative stabilities of Cu(II) species using a well plate, a student adds 6 drops 1M NH₃ to 6 drops 0.1M Cu(NO₃)₂. He observes that a blue precipitate initially forms, but that in excess NH₃ the precipitate dissolves and the solution turns blue. Addition of 6 drops 1M NaOH to the dark blue solution results in the formation of a blue precipitate.

a. What is the formula of Cu(II) species in the dark blue solution? Would this be a ligand exchange? So it would be something like Cu(NH₃)?

b. What is the formula of the blue precipitate present after addition of 1M NaOH? Another ligand exchange? Something like Cu(NaOH)?

c. Which species is more stable in equal concentrations of NH₃ and OH^-, the one in Part A or the one in Part B? Does this have something to do with coordination numbers? How do I tell which one would be more stable?