Are you titrating? Qualitative testing? Just what? If the copper is in solution you can filter the ppt (or let the ppt settle and decant some of the supernatant liquid) and to the filtrate or the decanted liquid add some more NaOH to see if additional ppt will form. If I have guessed wrong about the application just clarify what you're doing and repost.
The lab pertains to the copper cycle. The reaction is copper nitrate (aq) + 2NaOH (aq) -> copper hydroxide (solid) + 2 sodium nitrate (aq)
If I had not added enough NaOH, I know I wouldn't be getting enough precipitate, but I'm not sure I would be able to tell just by looking at it. The copper nitrate itself is a light blue color and the end result should be dark blue with precipitate, but there is still some surrounding light blue solution
If there is a pale blue color to the liquid, I would be skeptical that all of the copper hydroxide had been pptd. You can do one of two things. (Of course, some of the ppt may be very finely divided, hasn't settled, and that could be providing the color.) One is to let the ppt settle for a period of time. Then add, dropwise and without stirring, NaOH to the liquid above the ppt. Observe closely if a ppt forms when the drops of NaOH make contact with the solution. The other way is to just add an excess of NaOH so you KNOW all of the hydroxide has pptd.
Based on the information provided, it seems like you are conducting a qualitative test for the presence of copper ions in solution. In this case, you can follow these steps to confirm if enough NaOH has been added:
1. Begin by filtering the solution to separate the precipitate from the rest of the liquid. Alternatively, you can let the mixture sit undisturbed to allow the precipitate to settle at the bottom and then carefully decant the supernatant liquid (the clear liquid above the settled precipitate).
2. Once you have obtained the filtrate or decanted liquid, add a small amount of NaOH (sodium hydroxide) solution to it.
3. Observe the mixture after adding NaOH. If you have not added enough NaOH initially, the addition of more NaOH will result in the formation of additional precipitate. This is because the copper hydroxide precipitate is insoluble in water but soluble in excess NaOH.
4. Compare the color of the solution before and after adding more NaOH. Copper nitrate solution is typically light blue in color, while the copper hydroxide precipitate is darker blue. If you see an increase in the intensity of the blue color or the formation of additional precipitate, it suggests that you did not add enough NaOH initially and should continue adding more until no further changes occur.
Remember that these observations and tests are indicative and cannot provide an accurate quantitative measurement. If you need to precisely determine the amount of NaOH required for complete precipitation, a titration method would be more suitable.