Why the addition of NH3 should be precise in spectrophotometer reading? What if it gives darker color?

Answer 1

NH3 in what? darker color than what? What experiment are you doing? Details?

Answer 2

Spectrophotometer. 2 ml of NH3 is added to Cu(NO3)2 to give it dark blue color. If we accidantely put 3 ml of NH3, would the absorbance reading by spec should be considered? Explain.
I wrote we shouldn't consider the reading because it will give darker color than it should be and the reading would be beyond the expected range. Is that right?

Answer 3

You don't have all of the experimental details written for me; however, my best guess is that the NH3 is not the limiting reagent. That is, I suspect that the experiment is to eventually determine Cu and adding NH3 gives the dark blue color. If I'm right about that then 2 mL NH3 is enough to complex ALL of the Cu ion and still have NH3 left over. I don't know the total volume but I don't think 1 mL out of several will make too much difference except for the dilution. It won't make it darker but it could dilute it enough to be a little less intense color.