We can use Ecell to tell us about the thermodynamics of redo…
We can use Ecell to tell us about the thermodynamics of redox reactions in general, whether they are part of a voltaic cell or not. For example, metallic zinc, Zn(s), could react with molecular iodine, I2(s), to give zinc iodide, ZnI2. We can use the potentials for the two half reactions to determine Ecell and thus ΔG for this reaction to see if it would be spontaneous or not. ZnI2 is an ionic compound that is shown below with charges to make the nature of the redox reaction obvious. Zn(s) + I2(s) → Zn2+-I2(s) The relevant reduction half reactions wit their potentials are as follows (you will need to reverse one of these to convert it to an oxidation potential before performing your calculation): I2(s) + 2e- → 2I-(aq) Eo = +0.54 V Zn2+(aq) + 2e- → Zn(s) Eo = -0.76 V Use the data above to calculate Ecell and thus ΔGr. Assume that Eo values in aqueous solution are accurate enough to be used. ΔG = -n . F . Ecell F = 96,485 Coulombs/mol
Read Details