Relationship between cell potential and concentration

[Westlund2]

I did a lab using an electrochemical cell to establish a relationship between cell potential and concentration. I derived two equations from lines of best fit. One is Cell potential of Ag vs. Cu Concentration: y = -0.04520x+0.5515. The other is cell potential of Zn vs. Cu concentration: y = 0.03720x+0.7855.

Now I am supposed to derive a single equation from these two, to describe how the measured cell potential varies depending on the concentration of ions in the cathode half-cell and the concentration of ions in the anode half-cell.

Can someone give me an idea or help me out?

 

[Borek]

Have you tried if log(concentration) doesn't give better results?