Question

# So, I'm confused about finding E cell value Please explain me ! For example, Mn(s) ∣...

So, I'm confused about finding E cell value Please explain me !

For example,

Mn(s) ∣ Mn2+(aq) ∥ Ag+(aq) ∣ Ag(s)

overall reaction is Mn(s)+Ag+(aq) -> Mn2+(aq)+Ag(s)

Oxidation: Mn(s)->  Mn2+(aq)+2e- E: -1.18 I think here it should be 1.18 to calcuate because on the table, Reduction Half reaction is Mn2+(aq)+2e- -> Mn(s) and the order has been changed. WHY IT IS -1.18???

Reduction: Ag+(aq)+e- -> Ag(s) E: 0.80 This makes sense following by the table.

For another example, Sn(s) | Sn2+(aq) || Ag+(aq) | Ag(s)

Overall rxn: Sn(s)+ Ag+(aq) -> Sn2+(aq)+Ag(s)

Oxidation rxn: Sn(s)-> Sn2+(aq)+e- E=-0.14 Here, I think it should be 0.14 but why is it -0.14?????

Reduction rxn: Ag+(aq)+e- -> Ag(s) E= 0.80

E'cell=Ecatode-Eanode= 0.80-(-0.14)=0.94 Can I also calculate like E'cell= Ered-Eoxi?

People calcuated like E'cell= Ered+Eoxi. Why is that? #### Earn Coins

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