[desperado182]

my question is to calculate the concentration of NH3 at equilibrium

Cu 2+ + 4NH3 --> Cu(NH3)4 2+

A solution is made by mixing 20.0 mL of 1.00 M CuSO4 and 1.50 L of 0.570 M NH3. Assume additive volumes to answer the following questions.

the first thing I did was calculate the initial moles of CuSO4 and NH3: multiplying thier volumes by their molarities.

CuSO4's initial moles = .02
NH3's intial moles = .855

Then to calculate the final molarities, I divided the initial moles by the total volume (1.52)

final concentration of CuSO4 = .013
final concentration of NH3 = .5625

now, i don't know where to go from here. i know that:
Kf= [Cu(NH3)4]\[Cu][NH3^4]

i would really appreciate the help. thank you.

[AWK]

You should do stoichiometry of complex formation before calculation of ammonia concnetration.

[AWK]

ohh no.. how difficult

very easy - use your balanced equation
just 0.562 - 4 x 0.013 = 0.510

And this result is completely sufficient.