In testing the relative stabilities of Cu(II) species using a well plate, a
student adds 6 drops \(1 \mathrm{M} \mathrm{NH}_{3}\) to 6 drops \(0.1 \mathrm{M}
\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2} .\) He observes that a blue
precipitate initially forms (after the first few drops of \(1 \mathrm{M}
\mathrm{NH}_{3}\), but that in excess \(\mathrm{NH}_{3}\) (5 or 6 drops) the
precipitate dissolves and the solution turns decp blue. Addition of 6 drops \(1
\mathrm{M} \mathrm{NaOH}\) to the deep blue solution results in the formation
of a blue precipitate.
a. What is the formula of the Cu(II) species in the deep blue solution
obtained with excess \(\mathrm{NH}_{3} ?\)
b. What is the formula of the blue precipitate present after addition of 1 M
NaOH?
c. Which species is more stable in equal concentrations of \(\mathrm{NH}_{3}\)
and \(\mathrm{OH}^{-}\), the one in Part A or the one
in Part B?
_________
