On the basis of standard electrode potential values, suggest which of the following reactions would take place ? (Consult the book for E^@ value) (i) Cu+Zn^(2+)rarr Cu^(2+) +Zn (ii) Mg + Fe^(2+) rarr Mg ^(2+) +Fe (iii) Br_2+2Cl^(-) + 2Cl^(-) rarr Cl_2 +2Br^(-) (iv) Fe+Cd^(2+) rarr Cd +Fe^(2+)

On the basis of standard electrode potential values, suggest which of

1.	On the basis of standard electrode potential values, suggest which of the following reactions would take place ? (Consult the book for E^@ value) (i) Cu+Zn^(2+)rarr Cu^(2+) +Zn (ii) Mg + Fe^(2+) rarr Mg ^(2+) +Fe (iii) Br_2+2Cl^(-) + 2Cl^(-) rarr Cl_2 +2Br^(-) (iv) Fe+Cd^(2+) rarr Cd +Fe^(2+)
Answer» Solution :(i) `Cu^(2+)+Zn^(2+) rarr Cu^(2+)+Zn` `E^@ (Cu^(2+)\|Cu)=+0.34V,E^@(Zn^(2+)\|Zn)=-0.76V` `E_("cell")^@=E^@("CATHODE")-E^@("ANODE")` `=-0.76-0.34=-1.10V` Since `E_("cell")^@` s - ve, the reaction does not OCCUR. (II) `Mg + Fe^(2+) rarr Mg ^(2+) +Fe ` `E^@(Mg^(2+)\|Mg)=-2.37V,E^@(Fe^(2+)\|Fe)=-0.74V` `E_("cell")^@=-0.74-(-2.37)=++1.63V` Since `E_("cell")^@` is +ve, the reaction will take place. (iii) `Br_2+2Cl^(-) + 2Cl^(-) rarr Cl_2 +2Br^(-)` `E_("cell")^@ = +1.08""1.36=-0.28V` Sine `E_("cell")^@ ` is ve - , this reaction does not occur . (iv) `Fe+Cd^(2+) rarr Cd +Fe^(2+)` `E_("cell")^@=-0.44-(-0.74)=+0.30` Since `E_("cell")^@` is +v, therefore , this redox reaction will occur.