I am given a question where I have to state which combination of electrodes will result in the greatest voltage and which will result in the lowest voltage. The metals given are Zinc, Copper, Silver and Hydrogen
I think that silver and copper would give the greatest voltage and therefore zinc and hydrogen would give the lowest voltage due to their standard potential. would that be true?
2 answers
Correct
I may have misunderstood the question but I don't agree with your answer. Did you work out the voltage generated by each possible pair? And do you want the highest or lowest voltage, period, or do you that only for cells that are spontaneous? For the low voltage, for example, for spontaneous cells,
Zn ==> Zn^2+ + 2e Eo = +0.76
2H^+ + 2e ==> H2 Eo = 0
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Ecell = 0.76 and that is higher than the one below which you thought was highest.
But for Ag and Cu it would be
Ag^+ + e ==> Ag Eo = 0.8
Cu ==> Cu^2+ + 2e Eo = -0.34
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Eo = 0.46
Zn ==> Zn^2+ + 2e Eo = +0.76
2H^+ + 2e ==> H2 Eo = 0
-------------------
Ecell = 0.76 and that is higher than the one below which you thought was highest.
But for Ag and Cu it would be
Ag^+ + e ==> Ag Eo = 0.8
Cu ==> Cu^2+ + 2e Eo = -0.34
--------------------
Eo = 0.46
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