College Chemistry Lab: Galvanic Cells
I am doing a lab on galvanic cells for Chemistry. We made cells with Cu/Zn Mg/Zn, and Fe/Zn, all .1M. We were then told to assume the reduction potential of the Zn half cell was -.76, and have to find the reduction potential for the other three half cells. My voltage measurement for Zn/Cu cell was .278 V, What would the copper half cell voltage be? I get you use the Nernst equation, but my answers are far from the expected reduction potential of copper. I want to confirm I'm doing the problems right. I also got .0095 volts on the multimeter for zn/fe and .4355 v for zn/mg. My half cell answers were .482 for copper, -1.196 for magnesium and -.75 for iron.
The second part of the lab is to find the molarity of an unknown concentration of copper. We did zn/cu reactions, and varied the copper molarities for .1m, .01M, .001M, and .0001M. My answers were .288, .285, .273, .250 v respectively. We then have to make a calibration curve based on these number which should lead us to our unknown concentration for copper. I'm just how to represent the copper molarity on the calibration curve, because the number for molarity (.1, 01, .001, and .0001) can't all fit on x access. Do I need to do nernst for these part of lab and how do I do it?