# Calculating the Molarity of an Ion?

I'm completely stuck on this one - I was doing an experiment in a lab and now I cannot find the molarity of an ion in a solution. I've looked everywhere on the web but after 2 hours of searching I couldn't find anything. Maybe I am looking in the wrong direction.

I mixed three solutions: 1mL of $\ce{0.1M ~CuSO4}$, $\ce{0.28 M ~~NH3}$ and water. This solution turned into

$$\ce{Cu(H2O)4^{2+} + 4NH3 = Cu(NH3)4^{2+} + 4H2O}$$

This turned the solution from light blue to dark blue-ish purple. The final mL of the mixed solutions was 25 mL. Now I am supposed to calculate the molarity of the $\ce{Cu(NH3)4^{2+}}$ ion. I am pretty sure that I only have to calculate the molarity of $\ce{Cu^{2+}}$ but I am not entirely sure. If you guys could give me some help on this I would be very grateful.

• you need to know more information like the volume of the 0.1M solution and the volume of the final mixed solution to calculate the molarity of Cu(NH3)4^(2+) – DavePhD Mar 6 '15 at 18:53
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• I'm sorry! I did forget to add the volume - I will add it right now. – Mia Mar 7 '15 at 20:46
• Is the 1 ml also for the ammonia solution? – Binary Geek Mar 10 '15 at 10:08