Calculating molar concentration, mass percent, and concentration of the cation in unknown cupric solution.

Question

anonymous · Answer

I had a lab last week and after we were completely finished (everything had been disposed of and we were past the point of no return)  our professor pointed out that many of us were missing some key numbers to finishing the actual lab -__-
In the lab we were presented with an unknown cupric solution. Our goal was to determine the molar concentration, mass percent, and concentration of the cation. I don't even know where to begin!
I was given 2.13 g of cupric solution and I reacted it completely with NaOH (0.4M). . . don't know how much though :/
After I "cleaned" the percipitate and stuck it in the oven I came back with a mass of 8.563g (test tube originally weighing 8.52g)
I'm using the equation
CuX2+NaOH ->Cu(OH)2+2NaX
X being the unknown portion of my equation.

jfraser · Answer

you're right, you are past the point of no return. There's no way to determine the molar concentration, mass percent, or any other property of the solution if you don't know how much sodium hydroxide was used in the reaction. You'll have to do it again.

anonymous · Answer

I figured. Thanks for confirming though! 
Wish I could try the lab over again.