[Goddess]

Here is my question:

"What is the millimolar concentration of Cu2+ in a solution prepared by mixing 5-mL of 1.1 mM CuSO4 with 25-mL of 0.25 mM Cu2+ and diluting the mixture to 100 mL with water?"

I'm not sure how to approach this.  So far I've tried converting the mM for each to mmoles of each and adding them but I'm not sure they are additive.  Do I use the M1V1=M2V2 equation somehow?

Thanks in advance!
 

[Borek]

Sum amounts (mmol) of Cu2+ from both sources, then use M = n/V.

[Goddess]

So:

CuSO4 = 1.1mmol/L x 0.005L= 0.0055mmol
 
Cu2+   = .25mmol/L x 0.025L= 0.025mmol

total mmol Cu2+ = 0.01175mmol/.1L = 0.1175 mM Cu2+

[Borek]

Seems OK to me.