Potential Difference CR pg. 49

[Kaitlin Ross 3E]

When it says E(cathode)-E(anode)=E(cell) for the reaction with copper and zinc, the E(Cu)=0.34 and the E(Zn)=-0.76. Does the reaction and value for Zinc get flipped or would the values be plugged into the equation so the value would be 0.34-(-0.76)=1.1V?

[Fariha Hameed 1D]

You would plug the -0.76 V into the equation to get +1.1 V. The reason the equation is E^o_cell = E^o_cathode - E^o_anode is that all E^o values are written as reductions, but since the anode (Zn in this case) is oxidized, the equation accounts for reversing the E^o value by subtracting it from the E^o of the cathode. Hope this helps!