What is the cell potential for the reaction Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s) at 79 ∘C when [Fe2+]= 3.20 M and [Mg2+]= 0.310 M .
anode reaction: oxidation takes place
Mg(s) -------------------------> Mg+2 (aq) + 2e- , E0Mg+2/Mg = - 2.38 V
cathode reaction : reduction takes palce
Fe+2(aq) + 2e- -----------------------------> Fe(s) , E0Fe+2/Fe = -0.44V
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net reaction: Mg(s) +Fe+2(aq) -------------------------> Mg+2 (aq) + Fe(s)
E0cell= E0cathode- E0anode
E0cell= E0Fe+2/Fe - E0Mg+2/Mg
= -0.44 - (-2.38)
= 1.94 V
nernest equation
Ecell = E0cell -(0.0591/n)* log [Mg+2]/[Fe+2]
Ecell = 1.94 - (0.059 x1/2) *log (0.310 / 3.20 }
Ecell = 1.97 V
cell potential =Ecell = 1.97 V
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