Calculate the standard cell potential for each of the following electrochemical reactions:
a) the reduction of Sn(IV) to Sn(II) by Zn(s)
b) the oxidation of Sn(II) to Sn(IV) by dichromate ion in acid solution
c) the reduction of NO3- (negative sign there is superscript) to NO by cobalt metal
To answer all of these questions you will need a standard reduction potential table, which should be found in your chapter on electrochem or in an appendix of your text. What the table tells you is the amount of voltage needed to oxidize or reduce a given chemical.
For your first reaction you have Sn4+ being reduced to Sn2+ by Zn. This must oxidize the Zn to Zn2+ (this is the only cation for zinc). Thus the overall reaction is:
Zn + Sn4+ ----> Zn2+ + Sn2+
Each half reaction would ...
The solution is given step-by-step with short explanations.